http://www.epa.gov/otaq/stateresources/transconf/projectlevel-hotspot.htm

Project-Level Conformityand Hot-Spot Analyses

CE 253Guest Lecture

Jim Dunshee09-APR-2015

EPA Guidance Website:

TAQ 2015 Final Project Tips: Links & Contours

Goals1. Define link geometry for use in MOVES & CALINE

2. Generate pollutant concentration contour plots to visualize modeling results

MOVES/CALINE

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Background: Defining Links by Activity

Source: EPA-420-B-13-053

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Link activity can be characterized by:

Source: EPA-420-B-13-053

1. Average Speed2. Link Drive Schedule3. Op-Mode Distributions

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Example Roundabout Links(overly simple & low accuracy approach)

2 distinct link speeds and lengthsX 8 lanes= 16 total on-road links

• Avg speeds based on real-world data• Assumed avg speed decreases by 10mph

due to peak hour traffic congestion

23mpg avg Approach/Departure Link

16mph avg Roundabout Link

Off-Peak Hour Speeds Peak Hour Speeds

13mpg avg Approach/Departure Link

6mph avg Roundabout Link

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Background: Receptor Positions

CALINE4 v2.1 limited to 20 receptors per run

High receptor density will require multiple CALINE runs

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Low Receptor Density = Low Resolution Contours

Note: Ambient PM2.5 = 5.5 µg/m³; distances in meters

Sufficient data for contours will require dense grid of receptors, including placing receptors ON LINKS

Wind Dir.181°

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Goal 1: Defining Link Geometry

1. Determine study areaExample: ~0.5km² grid with intersection of interest near center

2. Use Google Maps (regular & “Style Wizard”) to generate images of links with known scales

Google Styled Maps Wizard: http://gmaps-samples-v3.googlecode.com/svn/trunk/styledmaps/wizard/index.html

3. Use MATLAB to determine XY coordinates within images

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Default: m by n pixels New: y by x pixels

y meters

x m

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sPixels as Built-in Scale

Now scale is built-in image property

Image = matrix of pixels = 1m x 1m each(easy to analyze in MATLAB)

Maintain aspect ratio

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Single Lane Road Edges from Google Map View Correspond Well With Actual Lane Centers

Can use this property to automatically detect & define links

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Find Area in Google Maps

Latitude, Longitude, Map Zoom Level

Right click for ‘Measure distance’ option

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Find Same Area in Styled Map Wizard

1. Enter Lat. & Long. coordinates into "Style Wizard”

2. Adjust slider bar to appropriate zoom level• Slider bar scale is 0-21• Generated image will be zoomed in by +1For example, if the you want 18z (approximately 552m width by 414 height) adjust slider to 17

http://gmaps-samples-v3.googlecode.com/svn/trunk/styledmaps/wizard/index.html

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Styled Google Static MapsRegular B&W (will be useful in MATLAB)

Done by removing layers & defining color schemes in “Style Wizard”

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Resize Image Pixels to Match Map Dimensions

http://www.picresize.com/

Default: 640 x 480 pixels New: 552 x 414 pixels

*552m

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*Approximate map dimensions with 4:3 aspect ratio at zoom = 18

Easily done here:

CAVEAT: check your dimensions

I also resized and sharpened the BW image simultaneously with this site

Maintain 4:3 aspect ratio

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Visually Define Link Geometry

Can use white lines in MS Paint to separate links

Use thin black lines to add more links or augment existing links

Remove features that are not of interest

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Analyze Image in MATLABMy code comments outlining steps to take:1. %Read in image2. %Convert image from RGB to grayscale3. %Plot histogram of grayscale image4. %Pick a threshold to separate histogram peaks

(50-100 should work for preprocessed image)5. %Index values below thresh as 0, and above as 1, to create BW image6. %Find groups of 8-connected pixels and label as objects7. %Create and display an RGB image with different colors for each object

Functions used:imread, rgb2gray, imhist, bwlabel, label2rgb

Tip:With bwlabel, it will be useful to define each labeled object, as well as the number of labeled objects: [label,num]

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Manual Threshold with Image HistogramSource: Bradford Smith, UVM ME207 Spring 2015 Lecture

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Labeling Objects in a Binary Image

http://www.mathworks.com/help/images/labeling-and-measuring-objects-in-a-binary-image.html

Sources:Bradford Smith, UVM ME207 Spring 2015 Lecture

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Individually Labeled LinksEach link is now an object labeled as a number (1:num of links)

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imshow(label==8)

Link 8Displaying pixels labeled as “8”:

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CALINE Limited to 20 Links/Run

num = 51

Can manually remove unnecessary links from image

May be better to keep the 20 link max. in mind when initially defining study area…

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16 LinksApproach/departure links within 100m of intersection.Beyond that, cruise links.

Cruise Links

Departure Links

Approach Links

I also realized that I should extend the departure links to avoid large gaps b/w links at intersection (necessary gap to separate links is only 1 pixel)

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Individually Labeled Links

num = 16

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Automatically Find Link Endpoints%Define start and end points for each link and store in matrixlinks = zeros(num,4); %initialize matrix “links” to store datafor i = 1:num %num = # of links [y1,x1] = find(xlabel==i,1,'first'); %left-most XY coordinate Of link [yn,xn] = find(xlabel==i,1,'last'); %right-most XY coordinate Of link

%Store coordinates in “links” matrix%Use negative Y values to convert from matrix to XY coordinates links(i,1) = x1; links(i,2) = -y1; links(i,3) = xn; links(i,4) = -yn;end%Write links geometry data to .xlsx filefilename = 'links.xlsx';xlswrite(filename,links);

Output:x1 y1 xn yn

Link 1

Link n

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links.xlsx

Rows = linksTop = firstBottom = last

Columns = x1, y1, x2, y2

1 -213 108 -2081 -223 109 -217

110 -208 216 -205111 -217 207 -214197 -1 204 -101203 -104 208 -202207 -1 213 -101209 -207 214 -317211 -214 318 -211213 -103 218 -212214 -319 219 -414218 -216 223 -317220 -205 317 -201223 -319 228 -414319 -201 552 -186320 -211 552 -195

Can copy & paste rows + columns into CALINE

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MATLAB Data Cursor

Useful, but keep in mind that top left of image has default [X,Y] coordinates of [1,1]

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Receptor Positions: Grid%Define X and Y as vectorsX = round(linspace(xmin,xmax,# of points));%Use negative Y values to convert from matrix to Cartesian coordinatesY = -round(linspace(ymin,ymax,# of points));%Create matrices of X and Y values[Y,X] = meshgrid(Y,X);%Convert matrices to vectors%Store vectors as coordinates in matrix “receptors”%Write coordinates to .xlsx file

x yReceptor 1

Receptor n

Output:

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432 Receptors = 22 CALINE RunsTook me ~15min of mostly copying & pasting (~40sec/run)

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Goal 2: Contour Plots

1. Copy CALINE receptor results into .xlsx file with corresponding XY coordinates

2. Import data into MATLAB

3. Superimpose contour plot onto area map

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CALINE Results

x y Pollutant ConcentrationReceptor 1

Receptor n

Can just copy & paste pollutant concentrations into previously made ‘receptors.xlsx’ file and save as new file (e.g., ‘receptors_PM.xlsx’):

This will serve as a “Z-coordinate”.Similar to making topographic/elevation map.

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Alternative to MATLAB: Result from JMP

Manually overlaid contour figure from JMP onto map image in PowerPoint

Imported my ‘receptors_PM.xlsx’ file into JMP and made contour plot

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MATLAB Contours: General Steps%Import the data%Convert y values from negative to positive (Cartesian to matrix coord.)%Create regular grid across data space[X,Y] = meshgrid(linspace(min(x),max(x)), linspace(min(y),max(y)));%create contour plot%flip Y axis to match image axes%add colorbar for scale of pollutant concentrationhold on%Read in map image and define as matrix Isubimage(I) %overlay map image onto contour plotalpha(0.58) %set transparency

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Default Colormap

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Transparency Affects ColorsTransparency = 0≤alpha≤1Previous slide: alpha = 0.58Here: alpha = 0.2

This is actually image map superimposed onto contour map (other way more difficult in MATLAB)

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A Solution to Match Colorbar to Colormap

Can place transparent rectangle(here: gray, 58% = alpha = 0.58)over the colorbar in PowerPoint

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“Hot” Colormap

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Lines Instead of Filled Contours

CHITTENDEN COUNTY, VT

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Good Luck!