Generate Running Routes from Image Outlines

Project a sampled image boundary onto a city map and connect the outline points with walking directions

Shape-running is the practice of planning a route whose GPS trace forms a recognizable outline when viewed on a map. This example extracts the boundary of a binary image, projects sampled outline points into a selected geographic region, and connects consecutive projected points using walking directions to produce a closed route.

Convert the imported image into a clean binary silhouette:

In[1]:=

targetImage=RemoveAlphaChannelColorReplace

,WhiteBlack,White;binaryImage=Binarize[targetImage,0.9]

Out[1]=

Extract the boundary pixel coordinates:

In[2]:=

edgeImage=EdgeDetect[ImagePad[binaryImage,1,White],2];pixels=PixelValuePositions[edgeImage,1];HighlightImage[edgeImage,pixels]

Out[2]=

Use

Nearest

and

FindHamiltonianCycle

to order pixels in sequence around the image outline:

In[3]:=

edges=DeleteDuplicates[Sort/@Flatten[Function[point,Module[{neighbors=Rest[Nearest[pixels,point,4]]},UndirectedEdge[point,#]&/@neighbors]]/@pixels]];cycle=Flatten[FindHamiltonianCycle[edges]];orderedPixels=First/@cycle;

Define a geographic region centered at the chosen location and use an angular span to control the size of the projected outline:

In[4]:=

centerLocation={41.90,-87.7};(*lattitude/longitudeofChicago*)spanDegrees=0.05;spanPadding=0.002;

In[5]:=

latMin=centerLocation〚1〛-spanDegrees/2;latMax=centerLocation〚1〛+spanDegrees/2;lonMin=centerLocation〚2〛-spanDegrees/2;lonMax=centerLocation〚2〛+spanDegrees/2;

Convert pixel coordinates to GeoPosition expressions:

In[6]:=

geoConversion[pixels_,imageSize_,centerLocation_,spanDegrees_]:=Module{latMin,latMax,lonMin,lonMax,width,height,latScale,lonScale},{{latMin,latMax},{lonMin,lonMax}}=centerLocation1-spanDegrees2,centerLocation1+spanDegrees2,centerLocation2-spanDegrees2,centerLocation2+spanDegrees2;{width,height}=imageSize;latScale=(latMax-latMin)height;lonScale=(lonMax-lonMin)width;GeoPosition[{latMax+(#〚2〛-height)*latScale,lonMin+#〚1〛*lonScale}]&/@pixelsgeoOutlinePoints=geoConversion[#,ImageDimensions[edgeImage],centerLocation,spanDegrees]&@orderedPixels;

Resample to use only every twentieth point, speeding up subsequent steps:

In[7]:=

geoOutlinePoints=geoOutlinePoints〚1;;-1;;20〛;Length[geoOutlinePoints]

Out[7]=

100

Visualize the resulting geolocations and the straight-line paths connecting them:

In[8]:=

GeoGraphics[{Red,PointSize[0.01],Point[geoOutlinePoints],GeoPath[GeoPosition/@Append[geoOutlinePoints,First[geoOutlinePoints]],"Geodesic"]},GeoRange{{latMin-spanPadding,latMax+spanPadding},{lonMin-spanPadding,lonMax+spanPadding}},GeoBackground"StreetMap",ImageSize500]

Out[8]=

Compute walking directions between consecutive points:

In[9]:=

consecutivePairs=Partition[Append[geoOutlinePoints,First[geoOutlinePoints]],2,1];routeSegments=Cases[Map[Quiet[TravelDirections[{#〚1〛,#〚2〛},TravelMethod"Walking"]]&,consecutivePairs],Except[$Failed]];

Display the connected walking-route segments on the street map:

In[10]:=

routePaths=Map[#["TravelPath"]&,routeSegments];GeoGraphics[{RGBColor[0.85,0.25,0.1],Thickness[0.009],routePaths},GeoRange{{latMin-spanPadding,latMax+spanPadding},{lonMin-8spanPadding,lonMax+8spanPadding}},GeoBackground"StreetMap",ImageSize500]

Out[10]=

Compute the total distance covered:

In[11]:=

dist=Total@Through[routeSegments["TravelDistance"]]UnitConvert[dist,"Miles"]

Out[11]=

84519.9

Out[12]=

16.0076

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Citation:
- Chen, Bryan. "Generating running routes from image outlines." Wolfram Community, Wolfram High School Summer Research Program, 2025.
- The outline image used in this example is based on the Tux penguin image from the public GitHub repository garrett/Tux.

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Contributed by: Wolfram Staff

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This work is licensed under a Creative Commons Attribution 4.0 International License

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Generate Running Routes from Image Outlines

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