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Conservation Applications of LiDAR

Engineering Applications of LiDAR Data

Workshop Exercises 2013

Ann Johnson, University of Minnesota Department of Civil Engineering

These exercises were developed as part of the “Conservation Applications of LiDAR” project – a series of hands-on workshops and online materials designed to help Minnesota GIS specialists effectively use LiDAR-derived data to address natural resource issues. The project is funded by a

grant from the Environment and Natural Resources Trust Fund, and is presented by the University of Minnesota Water Resources Center with expertise provided from the University of Minnesota, MN Department of Natural Resources, MN Board of Water and Soil Resources, and

USDA Natural Resources Conservation Service. More information is at http://tsp.umn.edu/lidar.

2 “Engineering Applications of LiDAR Data” Workshop Exercises

Engineering Applications of LiDAR Data Workshop Exercises

GETTING STARTED WITH LIDAR DATA .................................................................................................. 3

Importing Points from LiDAR Sources ....................................................................................................... 3

Working with .laz data .............................................................................................................................. 4

Importing Points from Other Sources ....................................................................................................... 5

Creating Surfaces ...................................................................................................................................... 5

Surface tools ......................................................................................................................................... 5

Editing Surfaces ......................................................................................................................................... 6

Manual surface edits ............................................................................................................................. 6

Editing surface properties ..................................................................................................................... 9

Adding to a surface: ............................................................................................................................ 10

Data clipping a surface: ....................................................................................................................... 10

Adding breaklines ............................................................................................................................... 11

Cropping a surface .............................................................................................................................. 11

EXERCISE 1: Using DEM Data in Design .............................................................................................. 13

Part 1: Importing a DEM with .adf files and creating a 3‐D digital terrain model surface ..................... 13

Part 2: Design ......................................................................................................................................... 18

EXERCISE 2: Using Shape File Data to Build a Surface ......................................................................... 22

Method 1. Use ArcMAP to convert contour files to a .dwg file. ............................................................ 22

Method 2: Create .shp files from the .gdb files in ArcMAP .................................................................... 23

Inserting Shapefiles using “Create Surface from GIS Data” ................................................................ 23

EXERCISE 3: Working with a geodatabase to build a surface .............................................................. 26

Part 1: Importing a DEM with .adf files and creating a surface ............................................................. 26

Part 2: Design ......................................................................................................................................... 28

EXERCISE 4: Using LAS files to build a surface .................................................................................... 30

APPENDIX: CIVIL 3D Basics ................................................................................................................. 32

Getting started ........................................................................................................................................ 32

Start a new drawing using the template option ................................................................................. 32

The Toolspace Panel and Prospector and Settings Tabs ..................................................................... 33

Setting the Coordinate System ........................................................................................................... 33

Labeling ................................................................................................................................................... 34

Add Photos as a Background ................................................................................................................... 35

Download air photos and add to your project .................................................................................... 35

Access Air Photos through a WMS Connection .................................................................................. 35

Using Points in Civil 3D ............................................................................................................................ 37

Displaying and Labeling Points ............................................................................................................ 37

Creating Points .................................................................................................................................... 37


GETTING STARTED WITH LIDAR DATA

ImportingPointsfromLiDARSources

Review the types and sources of data available

See “LiDAR File Formats and Data Types” available at z.umn.edu/lidarmaterials under the “Basics” section.

How to download the data

See “Basics Exercise 1: Accessing Minnesota LiDAR Data”, also available at z.umn.edu/lidarmaterials under the “Basics” section.

How to work with DEMs in Civil 3D

Follow directions in Exercise 1 below.

Files with metric units for elevations can be converted to feet using ArcGIS.

Data standards:

Defined by the MN Digital Elevation Committee

Based on the recent USGA Base LIDAR specification

< 15 centimeter RMSEs

2-foot vertical accuracy (95%) confidence

1-meter horizontal accuracy

See “Understanding LiDAR Accuracy”, a discussion topic on the Minnesota LiDAR Forum at z.umn.edu/lidarforum.

Coordinate System

UTM Zone 15, NAD83 horizontal datum

NAVD88 vertical datum (with units in meters)

Make sure to set your coordinate settings in each Civil 3D drawing before working. This is done on the “Settings” tab under “Edit Drawing Settings”, and is very important. (See “Civil 3D Basics at the end of this document.)

Stand-alone data viewers (free)

Qcoherent (www.qcoherrent.com)

Fugro EarthData (www.fugroviewer.com)

Sanborn( www.sandborn.com/technologies/lidar.asp)


Workingwith.lazdata

Data from the ftp site is available in .laz format, which is a compressed form of .las data.

The benefits of using LAZ files are that more points at a higher density come in with LAZ files than in DEMs. The points are on a 1 meter grid.

LAS files can be converted to Shapefiles and ASCI files

LAS files can be used to generate DEMs

LAS files can be exported to a .txt file

Directions for working with LAZ files is in a document named “LAS File Processing Using LASTOOLS” available on MnGeo lidar download site at ftp://ftp.lmic.state.mn.us/pub/data/elevation/lidar/tools/lastools/LAS_File_Processing_Using_LASTOOLS.pdf

After you have downloaded LASTOOLS, use the following command prompt chain to convert data in a laz file (which is in meters) to a .txt file in feet that can be used in Civil3D:

las2txt –i <file name.laz> -o <file name.txt> -parse xyz –sep comma – keep_class 2 8 – scale_x 3.280839895 –scale_y 3.280839895 – scale_z 3.280839895

Note: When entering this chain, do not include the “<” and “>” before and after the file names


ImportingPointsfromOtherSources

You can also transfer points from an ASCII (text) file or a Microsoft® Access database file to another file. You can convert the point data during the transfer, which can include changing the coordinate zone.

Importing points is a quick way to place points into a drawing. For example, if a surveyor collects point data using a data collector, the data can be downloaded from the collector as an ASCII (text) file and then imported into an AutoCAD Civil 3D drawing.

Before you can import, export, or transfer point data, you must specify a point file format for each file that point data is read from or written to. The point file format describes how the point data is stored in the file, i.e., point number, northing coordinate, easting coordinate, elevation, and description. These formats vary based on how the data was collected or generated. You can use the point file formats that are supplied with AutoCAD Civil 3D or create your own formats.

CreatingSurfaces

The main goal in working with any type of LIDAR data is to create a representation of a surface. Bringing in a point cloud – which includes many points above the surface -- may prove cumbersome and unnecessary if the bare earth surface can be generated instead.

Surfaces are created in Civil 3D using the “Surfaces” menu in the “Create Ground Data” panel. Or, surfaces can be created using the Prospector, by right clicking on the surface line under each project.

Examples of creating surfaces are included in the exercises at the end of these notes.

Exercise County Description

1 Nicollet Use .dem data in design

2a Chippewa Use .shp file data to build a surface

2b Chippewa Using a .gdb file to create a shape file

3 Chippewa Importing a DEM with .adf files and creating a surface

4 Chippewa Using .las data to build a surface

Surfacetools

Once a surface has been created, there are several tools that can be used to examine the data:

Finding spot elevations

Find “Annotate” tab

Then, “add labels”, select “Surface” then “spot elevation”

Select the point to label…this creates an actual label as a text object


Creating a “quick profile”

Find the “Analyze” tab

Select “quick profile” from the “Ground Data” panel

Select two points and then select the lower left hand corner for drawing the profile

Using Waterdrop

Select the surface

Find “Waterdrop” under the “Analyze” panel

Select a point on the map….watch where the water will go

Slope arrows

Slope arrows can be used to determine drainage direction. To change the display,

1. Select the surface name and right click, select “surface properties”

2. Under “surface style”, select the draw down next to the name, and select “copy current selection”

3. Under information, change the name to “slope analysis”

4. Change the display and slope options as directed in class.

EditingSurfaces

Surface data can be very large and cumbersome. To eliminate some of the points, you may choose to do some of the following.

Note that any edits made to a surface will show up in the “definitions” tab under “Surface properties”. Any edits that you do not want can simply be deleted here. Edits can also be moved up or down in hierarchy using the arrow keys.

The most basic steps in making a better surface model are in the Surface Properties dialog.

Manualsurfaceedits

The commands below can be used once a surface is built. They are used to subjectively edit the data or the surface TIN elements. All are accessed from the “Surface” tab, then selecting “Edit Surface” tab, or by selecting the surface itself.

1. Add line

2. Delete line

3. Swap edge

4. Add point

5. Delete point

6. Modify or move point


Note: move point will only move horizontally; modify will move in all directions

7. Minimize flat areas

Note: this will create a more accurate surface, forcing triangulation to work in the z direction instead of create flat planes

8. Raise/lower surface

9. Smooth surface

NNI: This adds points to the surface on the basis of a weighted average of nearby points. Kriging: This adds points to the surface based on one of five different algorithms.

10. Paste

This will replace the data on a surface with data from a new surface. Remember to paste a smaller surface into a bigger surface, and the newer surface into the older surface. The surface being pasted onto will be overwritten.

11. Simplify surface

This option is useful in LIDAR applications, as it allows the user to reduce the number of points used in the surface itself. To simplify:

Expand the Surface Name all the way down to “Definition”

Right click on the “Edits” option, and select “Simplify Surface”


Select the “Point removal” option, and then, “Next”

Keep the button selected for “Use existing border” and select “Next”.

At this screen, determine what percentage of points to remove and the maximum change in elevation desired. This value is the maximum change allowed between the surface elevation at any point before or after the simplify process has run.

Click apply and then “finish”.


Editingsurfaceproperties

1. Expand the Surfaces branch

2. Right click the surface name and select “Surface Properties”

3. Select the definition tab.

4. Under Definitions Option at the top of the dialog, expand “Build”

Under the Build option you can:

Copy deleted dependent object

When you select “Yes” and an object that is part of a surface definition is deleted, the information derived from that object is copied into the surface definition. Setting this option to “True” in the surface properties will let you erase polylines from the drawing file, while still maintaining the surface information.

Exclude elevations less than

Setting this to “Yes” puts a floor on your surface. Any point less than this value will not be included.

Exclude elevations greater than

This puts a ceiling value on your surface.

Use Maximum triangle length

This limits the number of narrow triangles drawn at the border of the site.


Addingtoasurface:

1. Select the surface to initiate the surface editing commands 2. Find “Add Data” in the “Modify” panel 3. Here you can add a DEM file, point file, or other data sources

Dataclippingasurface:

This can be done a variety of ways. One easy way is to “add a boundary” to the surface. This is done as follows:

1. First, draw a polyline that defines the area you want to “clip” on the surface 2. In Prospector, expand the surface name, all the way down to “definitions” option 3. Right click over “boundaries” and select “add” 4. Now, select the polyline you drew earlier to clip the surface.


Addingbreaklines

Adding breaklines is done in the same way as adding a boundary (see “Data clipping” above).

1. First, draw a line that defines the breakline you want to add (or identify the breakline from survey data)

2. In Prospector, expand the surface name, all the way down to “definitions” option

3. Right click over “breakline” and select “add”

4. Now, select the polyline you drew earlier.

5. The breakline has been added, and the surface should reflect that breakline addition

Croppingasurface

This is a different option than “surface clipping”. When cropping, a whole new surface is created, which can be useful when dealing with large data files.

1. Expand the Surface Tools drop down and select “Create cropped surface”

2. Specify a name for the cropped surface.

3. Select the ellipse next to the “select crop area” option, and type in “O” to specify an object

4. Select the polyline you created to border the new cropped area

5. Select inside the polyline when prompted for a point. The polyline will now be highlighted.

6. In Drawing for a New Surface option, select “create a new drawing”

7. Under “New surface name”, enter a new name

8. Then, select “create a new drawing” and pick the civil Imperial template file


Once in the new drawing, type “Zoom”, then “Extents” to see the new surface:


EXERCISE 1: Using DEM Data in Design

This project involves the design of a drainage channel and outlet structure in Nicollet County. The DEM files were obtained from the state lidar data set (http://www.mngeo.state.mn.us/chouse/elevation/lidar.html) and then manipulated using ARCGIS.

Data files for this exercise can be downloaded at z.umn.edu/lidarmaterials.

Part1:ImportingaDEMwith.adffilesandcreatinga3‐Ddigitalterrainmodelsurface

1. Open Civil 3D and create the new drawing and project entitled “Exercise 1 DEM county drainage structure.dwg”. Use the Autocad Civil 3D imperial template file.

2. Set the coordinate system. (See Appendix, p. 33.)

3. Connect to the background aerial photo tile for Nicollet County. (For more detail, see Appendix, p. 35)

Command: MAPCONNECT

Click on Add WMS Connection and specify http://geoint.lmic.state.mn.us/cgi-bin/wms?

Put the photo on a separate layer (suggested name: “Photo”), so that it can be frozen to speed regeneration and drafting time.

4. Next, bring in the point file from the data as follows:

From the Prospector, right click on “point cloud” and then “create point cloud”.

Accept the default name or enter another (click “next”)

Under “create a new point cloud database”, choose “ESRI ADF” data file

Populate the file screen with ALL THE FILES in the “dem” folder, under “Exercise 1”

Click “Next” and then “Finish”.

The point cloud is being created. This will take a while.


Click “Close”, and then a balloon will appear in the lower right telling you the point cloud is being created. The message will change when the point cloud is created.

When the point cloud is complete, click on the balloon message to zoom to the point cloud.

Change its name as follows:

Right click on Point Cloud (1) under the Prospector tab. Select the top line “Point cloud properties”, then click on the point cloud name. Change it to “LIDAR DATA”

You can change the properties of the point cloud display as follows:

In Prospector: Right click on the point cloud name, then select “edit point cloud style”.

Under the “display” tab, turn off the bounding box and points display options by clicking in the “visible” column:

5. Next, create the surface:

Right click on the point cloud “LIDAR DATA” listed in the Prospector and select “Add


points to surface”. Give the surface a name. Under “Surface style” select the contour interval.

Again, this will take a while.

When the surface is created, contours will appear.

6. To change the appearance of the point cloud, right click on its name in the Prospector tab, then, select “point cloud properties”. On the “Information” tab, select “no display” under the heading “Point cloud style”.

Here are some other ways to change the display:

In the Prospector, select the point cloud name under the “point cloud” tab

Right click and select the top option: “Point cloud properties”

Under “point cloud style” you can down drag on the style name, and select one of the following:

o No display

o Elevation ranges

o Grayscale intensity

o LIDAR Point Classification

o Scaled color intensity

o Single Color

o True Color


7. To change the contour appearance, go into the Prospector and select the surface name. Right click on it, then select “Surface Properties”.

Under “surface style” you can down drag on the style name, and select one of the following:

o No Display

o Border Only

o A Variety of Contour Intervals

o Contours and Triangles

o Cut and Fill Banding

o Elevation Banding

o Slope

o Slope Arrows

o Slope Banding

You can also create your own surface style by selecting the icon to the right of the surface style, and working through the many options. This would allow you to create a contour interval, for example, that is much smaller, such as 0.1 foot:


Civil 3D allows for editing the styles of many features in addition to surfaces and point clouds. In general, right click over the feature you want to edit and select “properties” option to edit.

NOTE: You can also create the surface directly from the DEM. Both methods result in the same type of feature. Creating a surface from the “DEM” as follows is much quicker:

In the Home tab, Find “Create Ground Data”.

Under the “surfaces” drop down option, select “Create surface from DEM”.

In the Grid Surface from the DEM dialog box, select file type “ESRI Binary Grid (*.adf)”. Then browse to the folder <dem_ft> and select the .adf file.

Click “open” and the DEM is created. This will take a while.


Part2:Design

8. First, determine a proposed centerline for the berm structure as follows:

Create a layer called “berm structure” and make it current.

Find a suitable area to place a berm structure and outlet.

Create an alignment for the structure as follows:

Using the “create line” command on the Draw panel, create a line indicating one or more portions of the berm. Then, use “create curve between two lines” to round out the corner. Make this series of lines and curves into a polyline using the PEDIT command and JOIN.

Create the curve using the “radius “ option and select a radius that fits the berm layout.

9. Define this centerline as an alignment as follows:

In the “create design” panel, select “Alignment”, then “create alignment from objects”

When prompted, select the line or polyline that make up your berm structure centerline. When prompted for stationing direction, accept the proposed or reverse it.

Determine a beginning stationing for your berm structure and enter it as shown:

10. Now, create the alignment for the outlet channel:

Create a layer called “outlet structure” and make it current.

Near the berm, find a suitable area to place the outlet channel.

Create an alignment for the outlet structure as follows:

Using the “create line” command on the Draw panel, create a line indicating one or more portions of the outlet channel. Then, use “create curve between two lines” to round out


the corner. Create the curve using the “radius “ option and select a radius that fits the outlet channel layout.

11. Define this centerline as an alignment as follows:

In the “create design” panel, select “Alignment”, then “create alignment from objects”.

When prompted, select the line or polyline that make up your outlet channel centerline. When prompted for stationing direction, accept the proposed or reverse it.

Determine a beginning stationing for your outlet channel and enter it as before.

12. To create a profile for your berm structure and outlet channel:

Select “Create design” tab and find “Profile” and then, “Create Surface Profile”.

Select the berm structure as the alignment you want to work with.

Accept the profile default name select the “ADD” button in the lower right hand corner.

Click on the “Draw in Profile View” button.

To name your profile view, click on the icon to the right of the “Profile view name” field, and in the box for “property fields” select “parent alignment”.

Now, select “create profile view” and select the point where you want the LOWER LEFT HAND CORNER to be for the profile graph. LEAVE room for the profile, and if you need to move it, use the correct command.

13. Now, create the finished ground profile:

First, draw all of the TANGENTS for your proposed profile using simple AutoCAD Line draw and the Transparent Command Bar (located on the right edge of your screen). This allows you to draw a line by typical Autocad methods, or by station and elevation, or by station and grade.

Once the tangents are complete, use the “create design” tab and find “profile” then “profile creation tools”. Select the grid for the profile you wish to work on when asked to select a profile view.

Give the profile a “name” and accept the default layers.

Once that is done, the “profile creation tools” toolbar will appear in graphics space. This can be accessed again in one of two ways:

1. By selecting your profile and then the “profile geometry editor”.

2. By selecting your profile and then right click over it, find “edit profile geometry”.

To develop the finished ground profile, use the tangent and curve buttons on the far left side of the toolbar. You can also use the “transparent” commands that are on the right edge of the graphics space. These allow you to specify the station, elevation, or grade from one point on the profile to another.

Note: when you are done creating the profile, you can finalize it by escaping out of the profile creation command prompt. If you are not done, you can edit the profile using the grips or by using the profile geometry editors.


Note: if you lose the Transparent Commands toolbar, you get it back by:

View Windows Toolbars Select “civil transparent”

To label any point on the profiles:

First set up the station offset label style for “profile views” as follows: In the Settings tab of the Toolspace, select “Profile View” then “Label Styles” then “Station Elevation” and finally the “Station and Elevation” label style. Right click over “Station and Elevation” to edit the label style.

Then, select “Annotate” and then, “Add labels”. Select “Profile view” labels, and the label type is “station offset”. Specify the station to label and the elevation, and you can drag the label anywhere on the profile view.

14. To create the sections and surface for the new embankment channel:

Reference the typical section in your notes. Civil 3D calls a typical section an “assembly” and the elements of each are called a “subassembly”.

Step one: create a main assembly.

In the Home tab, select “Create Assembly” from the “Create Design” tab

Select an insertion point anywhere on the screen

Now add the subassemblies:

1. You can either select one that is already complete, or make your own. To select one that is complete, choose from the “assembly” tab on the Subassembly palette.

2. You can create your own subassembly as follows:

Select from the list of objects the subassemblies that you want. For this project we will need:

● Shape Trapezoidal

● Basic cut slope

Insert each element and change the properties of each to match the typical section provided.

Rename this assembly “embankment assembly”

Now you can copy that “embankment assembly” and use it for the other types of assemblies you need. To do that, just use an Autocad commands.

For this assignment, we can also create a subassembly for the embankment channel.

Typically, the spillway will be cut 0.5 foot into natural ground, and placed on the edge of the embankment.

Note that an assembly has three elements: Points (P), Links (L), and Shapes. A point represents where an assembly connects to another object, a link is a surface that connects two points, and a shape represents a closed polyline and is used to determine quantities.


15. To create a corridor

A corridor is a 3D model of our alignment. We will create two corridors for this project.

A corridor is a combination of a horizontal alignment (a baseline), a profile, and an assembly.

To create a corridor:

1. From the home tab, select “corridor” then “create simple corridor”

2. You will need to specify one baseline, one profile, and one assembly

3. Name the corridor

4. Specify the layer that it goes onto

Select the baseline by left clicking on it: then, select profile

Now, a dialog box will pop up that asks you to specify the target surface to connect the slopes to.

Do this by clicking on “Surfaces” and then selecting “surface 1”, or whatever the LIDAR surface is called in this drawing (note the “click here to select all” option”)

Note now that the corridor is built.

Remove all sections that go through an intersection by selecting the corridor (left click on it) and then right click and select “corridor properties”

Also note that here you can change the frequency of application of each assembly. For example, through a curved section, you can change the frequency to 10’.


EXERCISE 2: Using Shape File Data to Build a Surface

All of the files needed for this exercise are in the “Exercise 2” folder of the files available at z.umn.edu/lidar materials .

There are at least two ways to convert .shp files: both require ArcMAP.

Note: when using LiDAR data in .shp file format, there are two required steps. First, bring in the graphic representation of the data (i.e. points or contours). Second, attach the elevation information.

Method1.UseArcMAPtoconvertcontourfilestoa.dwgfile.

First, the .shp file must be converted for use in Civil3D as follows:

1. Open a new (blank) ArcMap document.

2. Load the contour data by clicking “Add Data” . Navigate to the Exercise 2 folder named “shapefiles”, select the file named “Contours.shp”, and click “Add”.

3. With the contours added to the map, add a basemap such as an aerial photo to check that the location of the contours has been added properly.

4. Then either use the “information” button or open the “Attributes table” to view elevations and to ensure they have come in properly.

5. After ensuring that all data has been added correctly, right click on the contours in the “Table of Contents” and go to “Data” then “Export to CAD”

6. Then set your folder destination where the DWG should be saved and select the version of CAD you wish to save in (2004, 2007, 2010, etc.). Name the file “Chippewa Contour elevations”.

7. When the DWG is finished generating it will appear on your ArcMap and should fall right on top of your current shapefile in ArcMap.

8. You can then open the DWG separately in an AutoCAD application.

This process will generate 3D contour lines. The elevation becomes embedded into the file when you export it out of ArcMap.

9. Now, in Civil 3D, open the “Chippewa contour elevations” drawing.

10. Create a new surface:

In Prospector, right click over the surfaces, and select “Create Surface”. (Choose the default TIN surface as the type.)

You can rename the surface now by placing the cursor in the “Value” cell of the name property; or rename it later, by right clicking over the name, selecting “Surface Properties”, highlighting over the name, and changing it.

Now, add data to the surface, by expanding it (double click on the name) and then


expanding the “definition” menu. Select the “contours” option and then right click over it to find “Add”. Give the Contour Data a description. Click OK.

When prompted to select the source of the data, click and drag a window over all the contours that were brought into the drawing.

Proceed with design now that you have the surface data. Note, since this .dwg file was created in ArcMAP, there are no pre-set layers or styles.

Method2:Create.shpfilesfromthe.gdbfilesinArcMAP

In ArcMAP drag the .gdb file and export the contours as a .shp file.

Create a new drawing called “Exercise 2 chippewa.dwg”

Import the .shp files as follows:

MAPCONNECT

Find “Add SHP Connection”

Browse to the chippewa.shp files that are in the exercise 2 folder.

Select “Add to map”

InsertingShapefilesusing“CreateSurfacefromGISData”

Note: Civil 2010 users must download Advantage Pack from the Subscription Site to use this method.

Use this method to import LiDAR data in the shape file format.

1. Click on Surfaces and select “Create Surface from GIS Data”

Note:

If your only source of LiDAR is through a whole county data set, you will want to create a selected area of interest using a polyline in your drawing.

If you don’t want LiDAR to blanket over your survey data, you may want to create an area of interest which will exclude your topo.


2. Here is where you can name the surface, select your style, layer, etc. When finished, select “Next”.

3. At this screen, you can select the data source – in this example I selected SHP. Then browse to your .shp file location. Next, select the “Login”

4. At this screen you need to select and check the box of the feature class you wish to import into your drawing. Here is where you can select a coordinate system for the .shp file and/or your own drawing. Select “Next” when finished.


Use for small data sets; not the whole county. Use with crossing only. Selects all contours touched by fencing line.Use with crossing only.

Only selects contours that are completely within the selected area.

I use this type all the time.

5. This is where you can define your area of interest, either by a pre-defined area that you have already created in the drawing (as explained in step 1), or just by using the default polygon. Select “Next”.

6. Here is where you select the elevation field so that your surface will have correct elevations to TIN and not be flat at zero elevation. You may have to widen the field in order to read the choices. Select the elevation field in the Civil 3D Property column. You can also save the file to a specific folder, if you wish. Select “Finish” when done.

7. Do a “zoom extents” to see your surface has been created with the proper elevations.


EXERCISE 3: Working with a geodatabase to build a surface

This project is also in Chippewa County. All of the files you need are in the “Exercise 3” folder of the files available at z.umn.edu/lidar materials.

The DEM files in the “Exercise 3” folder were obtained from the state LiDAR data ftp site (http://www.mngeo.state.mn.us/chouse/elevation/lidar.html) and then manipulated using ARCGIS.

Part1:ImportingaDEMwith.adffilesandcreatingasurface

1. Open Civil 3D and create the new drawing and project entitled “Exercise 3 chippewa county project.dwg”. Use the Autocad Civil 3D imperial template file.

2. Connect to the background aerial photo for Chippewa County using one of the methods described in the appendix (page 35).

3. Bring in the point file previously downloaded from the “Exercise 3” folder:

a. From the Prospector, right click on “point cloud” and then “create point cloud”.

b. Accept the default name or enter another. Click “next”.

c. For data, choose “ESRI ADF” data file.

d. Browse to the “Chippewa Files”

e. Populate the file screen with ALL THE FILES in the “dem011” folder, under “Exercise 3”


f. Now, your computer will give you a message that it is creating the point cloud. This will take a while (several minutes).

g. When the point cloud is complete, change its name as follows: Right click on Point Cloud (1) under the Prospector tab. Select the top line “Point cloud properties”, then click on the point cloud name. Change it to “LIDAR DATA”

h. You can change the properties of the point cloud display as follows:

In Prospector: Right click on the point cloud name, then select “edit point cloud properties”

Under the “display” tab, turn off the bounding box and points display options:

4. Next, create the surface:

Right click on the point cloud listed in the Prospector, under “point cloud” and select “Add points to surface”. Select the type of contours you want to show (1’ and 5’ background)

Again, this will take a while.

When the surface is created, contours will appear.

5. To change the appearance of the point cloud, right click on its name in the Prospector tab, then, select “point cloud properties”. Select “no display” under the heading “Point cloud style” which is on the “Information” tab.

6. To change the contour appearance, go into the Prospector and selecting the surface name, then right click and select “Surface Properties”.


Part2:Design

Find the existing drainage channel in the southern portion of the surface. Now, use AutoCAD line draw commands to create the alignment. Draw the lines on top of the photo, after creating a layer called “channel”.

Estimate the radius of the curves, and use the “curve between two lines” command to generate the alignment.

1. Create an alignment as follows:

In the “create design” panel, select “Alignment”, then “create alignment from objects”

When prompted, select the line or polyline that make up your outlet channel centerline. When prompted for stationing direction, accept the proposed or reverse it.

Determine a beginning stationing for your outlet channel and enter it as before.


2. To create a profile of this channel:

Select “Create design” tab and find “Profile” and then, “Create Surface Profile”

Select the “channel” as the alignment you want to work with.

Accept the profile default name select the “ADD” button in the lower right hand corner

Click on the “Draw in Profile View” button

To name your profile view, click on the icon to the right of the “Profile view name” field, and in the box for “property fields” select “parent alignment”

Now, select “create profile view” and select the point where you want the LOWER LEFT HAND CORNER to be for the profile graph. LEAVE room for the profile, and if you need to move it, use the correct command.


EXERCISE 4: Using LAS files to build a surface

This project is also in Chippewa County. The laz files in the “exercise 3 and 4” folder were downloaded from the MnGeo website ftp://ftp.lmic.state.mn.us/pub/data/elevation/lidar/ .

1. Run the laz files through the lastools.exe program:

At the command prompt, change the directory to the location of lastools.

Select las2txt.exe, convert the laz file to a txt file, and convert meters to feet in the same step by using the string shown in the image below and provided in the section “Working with .laz data” on page 4.

2. Input the points as follows:

Create ground data

Create point cloud

Select any point cloud format that is x, y, z with comma delimited (or space delimited if you transferred them to an excel spreadsheet)

Navigate to the output file you specified in LASTOOLs and change the coordinate system


Specify the coordinate system: UTM83-15F

You will have to wait as the point cloud is created.

Once the point cloud is created, you can add it to the surface.


APPENDIX: CIVIL 3D Basics

Gettingstarted

Startanewdrawingusingthetemplateoption

Select: File > New > Drawing

Select the AutoCAD Civil 3D Imperial template file:

Using a generic template file is a good choice because the layers and settings for label styles, etc. are already created. Your agency may have its own template that is to be used.

If a drawing has been created through other means, or has not been set up using a template file, the template can still be added using the “Manage” tab in Civil 3D.

In the “styles” panel, find “Import” then navigate to the template file you desire.


TheToolspacePanelandProspectorandSettingsTabs

All of the project elements are controlled and accessed through the “Toolspace”. This panel is located in the upper left hand corner of the Civil 3D screen. Within the Toolspace, study the “Prospector” tab and the “Settings” tab. This is where you will access many functions. See AutoCAD Civil3D tutorials for more details about these components.

SettingtheCoordinateSystem

Set the coordinate system for your drawing right away, before doing any work. This is done as a “Project Setting” as follows:

1. Select the “Settings” tab on the Toolspace Panel

2. Right click on the drawing name and select “Edit Drawing Settings” 3. Select the “Units and Zone” tab. Specify the “Category” and “Available Coordinate System”

to match the data being imported. For Minnesota LiDAR data you will usually select UTM83-15F (which is UTM Zone 15, NAD83 horizontal datum). However, there are exceptions, so check the metadata for the data you will be importing to confirm the coordinate system. For example, data from the City of Minneapolis uses UTM27-15F.

Once this is done, any LIDAR data you import will be adjusted for the correct coordinate zone.


Labeling

To add labels, use either the MTEXT command, or Annotate options.

MTEXT creates a free-standing multiline text object, while Annotate>Add Labels creates labels attached to other objects.

To use MTEXT:

type at command prompt, or find MTEXT on the Annotate or Home Tabs

Or, use auto labeling:

First, set up the label styles you need.

Find the “Annotate” tab on top

See “Add Labels” on far left, and select the label icon on the top. You can also use the “Add Labels” command on the bottom half of the button.

By using the template, the label styles are already created. You can edit them for labeling surfaces and alignments.


AddPhotosasaBackground

Air photos can be used as a background by either downloading them or accessing the remote images on the MnGeo server. The advantage of the former is that the images are always available, even when you don’t have internet access. The advantage of the latter is you don’t have to store and manage the very large image files.

Downloadairphotosandaddtoyourproject

1. To download county tiles, go to the http://www.mngeo.state.mn.us/ website.

2. Find “Air Photos” under the “popular resources” box on the right.

3. Select the “FSA Photos” button.

4. Then click on “2010” under the “Download County Files” option.

5. Select the county you want. A zip file will download, and you need to bring the “.sid” file into a directory on your hard drive.

6. In Civil 3D, type MAPCONNECT, then under the “Add Raster Image” option, select the .sid file you want to bring in, and then click on “CONNECT” and “ADD TO MAP”. Put this photo on its own layer that can be frozen to speed up drafting time.

AccessAirPhotosthroughaWMSConnection

1. In Civil 3D, type MAPCONNECT, then under the “Add WMS Connection” , specify either of these two WMS connections:

http://geoint.lmic.state.mn.us/cgi-bin/wms? for the entire state map

or

http://geoint.lmic.state.mn.us/cgi-bin/wmsz? for the MN state quadrangle map

2. Click “Connect”

3. At the prompt to “enter user name & password”, leave both fields blank and click “Login”


Then, select the box next to “2010 Schema” and “Add to Map”

4. Use <Shift> and the left mouse to select the image and then use DRAWORDER to move the photo to the back of the drawing.

5. To reduce the size of the raster image: zoom in or out to the size of the photo image you want showing, then, in MAPWSPACE, right click on “resample raster”. This will be the size until you “resample” again.

Note: Typing “MAPWSPACE” will bring up the map data task pane. This is similar to the ArcGIS data layer window. Any command in MAPCONNECT can be replicated in the MAPWSPACE task pane.


UsingPointsinCivil3D

In AutoCAD Civil 3D, you can create, work with, and manage points using a variety of commands and tools.

The points created by AutoCAD Civil 3D are called Coordinate Geometry (COGO) points, which are very different from AutoCAD point nodes. AutoCAD point nodes have only coordinate data (XYZ values) associated with them. However, COGO points, in addition to coordinate data, have a variety of properties associated with them, including point number, point name, raw (field) description, and full (expanded) description. Unlike AutoCAD point nodes, which exist in a single drawing, COGO points can be stored in a project outside a drawing and referenced by multiple users. In AutoCAD Civil 3D, the term point refers to a COGO point, not to an AutoCAD point node.

DisplayingandLabelingPoints

To control the appearance of a point symbol in a drawing, either select a default point symbol, or create a point symbol.

CreatingPoints

Choose from many point creation commands to create points. For more information, see the AutoCad tutorial “Creating Points”. You can also create points by importing point data from a file.

Version date: May 2013

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