Need help with Converting Bridge Point Data to Rectangular Polygon Shapes in ArcGIS Pro

Question

Hello, everyone!

I’m working with a shapefile that contains data for 233 bridges in point format. My goal is to convert these points into rectangular polygons to visualize them as top-down views, representing the footprints of the bridges.

I am new to ArcGIS Pro and would really appreciate any advice on how to achieve this. Has anyone worked on a similar task, where they converted point data to polygons (rectangular shapes)? If so, can you please share some tips or guide me through the steps?

Additionally, if anyone knows of any YouTube tutorials or resources that cover similar cases or this type of workflow in ArcGIS Pro, I would love to check them out.

Thank you in advance for your help!

BobBooth1 · Accepted Answer

Do you have any other data about the bridges?

If not, the simplest (if somewhat boring) approach would be to add a good imagery layer, zoom to each bridge point in turn, and manually digitize polygons into a polygon feature class. Put on some music and enjoy digitizing. It might take a few hours.

This tutorial shows adding a polygon feature:

https://learn.arcgis.com/en/projects/edit-features-to-create-enumeration-areas/#edit-polygon-features

If you don't have a suitable imagery basemap service, you may be able to download imagery and georeference it to your project area. This tutorial shows how to georeference an image.

https://learn.arcgis.com/en/projects/georeference-imagery-in-arcgis-pro/

You could also try using deep learning tools to detect bridges.

This tutorial shows how to use TextSAM:

https://learn.arcgis.com/en/projects/detect-objects-with-text-sam/

There are a number of pre-trained models that you can download here:

https://livingatlas.arcgis.com/en/browse/?q=pretrained%20model#q=pretrained+model&d=2

Depending on what data you have, you may have other options. For example, if you have an accurate roads layer, you could select sections of the roads at the bridge point locations (perhaps buffer the bridge points and use the bridge buffers to clip the roads layer). Then you could buffer the road segments at the bridges.

This would give polygons at the bridges aligned with the roads. That might be good enough, or something to start working with.

BobBooth1 · Accepted Answer

You could use Python. See the help sections on reading and writing geometries.'

https://pro.arcgis.com/en/pro-app/3.3/arcpy/get-started/reading-geometries.htm

https://pro.arcgis.com/en/pro-app/3.3/arcpy/get-started/writing-geometries.htm

You could read in the points and their attributes into a list using a search cursor, and then write out the geometry features to a new polygon feature class using an insert cursor:

https://pro.arcgis.com/en/pro-app/3.3/arcpy/get-started/data-access-using-cursors.htm

This approach will require you to learn some Python.

There are examples in the help topics. For example, see:

https://pro.arcgis.com/en/pro-app/3.3/arcpy/get-started/writing-geometries.htm#:~:text=created%20from%20a%20list%20of%20coordinates

There is an old example here that shows the sort of math you'll need to use:

https://gis.stackexchange.com/questions/271544/generating-polygons-from-centroids-with-rotation-and-dimensions

There is also Python code you can look at for making geometries in this (no longer maintained GitHub repo):

https://github.com/Esri/military-tools-geoprocessing-toolbox

See the scripts folder:

https://github.com/Esri/military-tools-geoprocessing-toolbox/tree/dev/tools/militarytools/esri/toolboxes/scripts

BobBooth1 · Accepted Answer

You might also look at this tool:

https://pro.arcgis.com/en/pro-app/latest/tool-reference/defense/coordinate-table-to-line-of-bearing.htm

Could making a line from the points distance and bearing and then buffering it to get the width.