importing a cad drawing- watercad v8i

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Importing A CAD Drawing Using Modelbuilder [TN]

Applies To

Product(s):

Bentley WaterCAD, Bentley WaterGEMS, Bentley HAMMER,

Bentley StormCAD, Bentley SewerCAD, Bentley SewerGEMS,

Bentley CivilStorm

Version(s): 08.11.XX.XX

Environment: N/A

Area: Layout and Data Input

Subarea: N/A

Original

Author:Jesse Dringoli, Bentley Technical Support Group

OverviewSome older versions of the Hydraulics and Hydrology product line (WaterCAD, WaterGEMS, StormCAD and

SewerCAD) used a much different procedure for converting "polylines to pipes", compared to the 08.XX.XX.XX

versions. This TechNote provides tips and techniques for effectively importing a CAD drawing into V8 XM or V8i

using the new method. This procedure is similar for WaterCAD, WaterGEMS, HAMMER, StormCAD, SewerCAD,

SewerGEMS, and CivilStorm.

BackgroundIn older versions of WaterCAD, WaterGEMS, StormCAD and SewerCAD, the user would import a CAD drawing

(.dxf or .dwg) via File > Import > Polyline to Pipe. Upon release of the V8 XM edition, this functionality was

merged into Modelbuilder, which is a powerful tool used to import many different types of data. Since the steps

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for a CAD drawing, which could initially cause some confusion to new users of V8 XM and V8i.

Preparing the CAD Drawing

1. First, you should take some time to clean up your CAD drawing prior to performing the conversion. Look for

entities that should not be converted, such as leader lines, and move them to their own layer. Turn off or remove

layers that you do not wish to convert. Do a quick review of your drawing and correct any potential conversion

problems that you may find.

Note: It is recommended that you perform a "save-as" before cleaning up the drawing, so

that you can retain the original.

2. Next you will need to save your CAD drawing into a DXF format, as this is the only format that Modelbuilder

currently accepts. DXF is the "drawing exchange format", so almost all CAD programs have the ability to save to

it. Whenever possible, try to save to the earliest DXF format, for better compatibility. For example, in AutoCAD,

go to File > Save As, and choose "2004 DXF" as the format.

Importing Your CAD Drawing Using Modelbuilder

Note: This process remains the same whether you are in the standalone, AutoCAD,

Microstation, or ArcGIS platform.

Note: This process assumes that you have certain pipe diameters separated by layer.

Note: This process assumes you're using V8i. If you're using V8 XM instead, the steps

in the Modelbuilder process will look slightly different. The basic process remains the

same, though.

1. Open WaterCAD/GEMS and start a new project. Ensure that the correct unit system is specified.Go to Tools >

User Data Extensions.

2. Right click on "Pipe" and choose to create a new user data extension. We will import the layer name into this

field so that we can assign diameters at a later point. Give it a name, keep the default data type of "Text" and

click OK.


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3. Start Modelbuilder by going to Tools > Modelbuilder. In the main window, click the "New" button to start a

new Modelbuilder run.

4. In the first step, select "CAD Files" as the Data Source type and browse to your .dxf file. Once selected, a table

will be displayed in the lower left corner, showing all the layers that exist in the drawing. Layers that you would

like to be imported should be checked. Unchecked layers will not be imported. The layer type will be displayed

after the name of each layer, showing you if the layer contains points, lines, or polygons. In this example, we

have checked only the layers that represent water distribution pipes of various diameters. Layers containing

roads, annotations and other irrelevant items have been unchecked:


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Note: If you have a lot of layers that need to be unchecked, you can right-click

anywhere in the list and choose "clear selection".

Note: In many cases, nodal elements such as tanks, pumps, etc are represented in a CAD

drawing as a series of lines. In this case, they cannot be imported as their respective

nodes in the modelbuilder process. The user must enter these elements later on after

the import.

5. Click the Next button to proceed to the second step. In this step, you should select the appropriate unit and

also make sure the check box next to "Establish connectivity using spatial data" is checked. This option allows

Modelbuilder to use the spatial information inside the CAD file (lengths, coordinates of endpoints/bends, etc) to

build the model, instead of the user needing to explicitly specify the start/stop node (which is typically not

possible for a CAD drawing.)

In addition to this, the "Tolerance" field will allow Modelbuilder to automatically connect pipe end points that

are within the specified value. Make sure "Create nodes if none found at pipe endpoint" is checked. In most

cases, only polylines are imported from a CAD drawing, so you'll want junctions to be created at the ends of

these.


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For the "Tolerance" options, take the following CAD line for example:

In this zoomed-in view, notice that a gap exists due to drawing imperfections. This gap is 1.5ft wide.

Now, if we import this CAD file with 1ft set as the tolerance, it will create two nodes at the actual end

points of these pipes:


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This is because the distance between the end points was not within the tolerance. If we were to instead

import this drawing with a 2ft tolerance, it would connect these end points and join them at a junction:

6. In the next Modelbuilder step, you will only need to keep the "Add objects to destination if present in

source" box checked, since we are creating new elements based on the CAD drawing data.

7. In the next step, accept "Current scenario" and "Label".

8. In the next step, you must configure how the data in each layer is mapped to WaterCAD/GEMS. Click each

layer from the list on the left and then configure the attributes on the right:

"Table Type"

This is used to select the type of element that a layer will be imported as. For a CAD file, you will most likely be

importing polylines only. So, this field will be set to "Pipe" (for WaterCAD, WaterGEMS and HAMMER) or

"Conduit" (for SewerCAD, SewerGEMS and CivilStorm).


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This is the field used to create labels for the elements created by the modelbuilder process. It is also used to link

up elements when updating existing ones. In the case of importing a CAD drawing, most likely a field containing

unique labels does not exist for the polylines. So, you should select "" for each layer. This will cause

Modelbuilder to automatically generate unique labels, utilizing a combination of an element's layer type label, its

shape type, and a numeric ID that represents the order in which it was created.

"Start"/"Stop"

Choosing the "Establish connectivity using spatial data" causes the connectivity information to be taken from the

CAD drawing, so you do not need to specify a start/stop node field for the pipes/lines. So, simply leave these as

"".

"Attribute"

At the bottom right corner of this Modelbuilder step, the user can link fields in the source data to fields in the

program. In the case of a CAD drawing, typically there are no additional, useful attributes. However, you could

link the "Layer" field to the user data extension attribute that you created in step 2. In this example, the user data

extension was named "AutoCADLayer":

By linking this field, there will be an attribute in the WaterCAD/GEMS model that contains the name of the layer

that the pipe came from. Later on this will be useful.


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Note: Make sure that you set the key/label field and "layer" mapping for each layer. If

your DXF contains points, they will show up as separate layers on the left side. You

can then click and assign them to a node element type such as Junction.

9. In the last Modelbuilder step, choose to build the model. Modelbuilder will then import the layers and

provide you with a summary, including a "Messages" tab that you can use to view informational messages about

the import process. In this case, there are some messages about nodes being created due to missing start/stop

nodes. This is expected since we were only importing polylines, with the "Create nodes if none found at

endpoint" option selected.

10. After closing the summary and closing Modelbuilder, you will be prompted to synchronize the drawing.

Choose "Yes" and your model should show up in the drawing area. If it does not, then go to View > Zoom >

Zoom Extents.


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Note: Upon completion of your ModelBuilder run, it is suggested you use the Network

Navigator tool to identify any connectivity or topological problems in your new mode

Assigning Pipe DiametersNow that our model has been created, we can assign diameters to the pipes, based on the layer attribute that

we imported.

1. Open the pipe flextable via View > Flextables.

2. Click the yellow Edit button ( ) and add your user data extension. To do this, first find it in the list on the

left side, click on it, and then click the single arrow button pointing to the right side. Click OK and you will now

see a column in the flextable, containing the layer that each pipe came from. In our example case, the layer

"12_WATER" represents 12" pipes, "16_WATER" represents 16" pipes, and so forth.


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3. Right click on any of the column headers, choose "Filter", and select "Custom". In the query window, double

click on your user data extension field from the list on the left and click the equals sign button. Then, click the

green button on the top-right corner to retrieve a list of unique values from this field. Double click on one of the

diameters (layer names) shown. In our example case, we'll start with the 10" layer:


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When you click OK in the query window, the flextable will be filtered to only show pipes that came from the layer

that you queried on (those from the "10_WATER" layer in our example case.)

Note: After performing your filter, the bottom left corner of the flextable will show

you how many pipes met the query condition and are displayed (for example "68 of 4714

elements displayed")

4. Now, assign the correct diameter by right clicking on the "Diameter" column header and choosing "Global

Edit". Keep the operation as "Set", and enter the appropriate diameter as the value. Click OK and your diameters

will be assigned.

5. Repeat steps 3 and 4 for each layer, assigning out all your diameters.

Note: When done, you can reset your filter by right clicking on any column header and

then choosing Filter > Reset.

Note: An alternative way to assign diameters would be to bring each layer in one by


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Prototypes, and set the pipe diameter to the smallest one in your CAD Drawing. Next,

uncheck all layers in the first Modelbuilder step except for the one corresponding to

that diameter. Import the pipes per above and they'll be assigned the diameter

specified in the prototype. Next, change the pipe prototype diameter to the next size,

open the Modelbuilder run again, uncheck the first diameter and check the next one.

Continue on like this for each diameter.

See AlsoProduct TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External LinksWater and Wastewater Forums

Bentley Technical Support KnowledgeBase

Bentley LEARN Server


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importing a cad drawing- watercad v8i

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bentley stormcad

bentley sewercad

bentley hammer

bentley sewergems

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