DGN to GIS with Affine Processor

ZachCrimmins — Sat, 19 Apr 2025 18:25:04 GMT

I work in Colorado where it's common for project survey data to be delivered in truncated state plane coordinates. Truncated meaning the surveyors remove between 1 and 3 million feet from the N: & E: coordinates. If not adjusted for, CAD linework shows up somewhere in AZ generally. I have been trying to define a workflow to get project data lined up in ArcGIS and have been having a heck of a time. Our CADD is done in Bentley OpenRoads Designer primarily.

In CAD, I get my aerial background to consistently line up with the data by assigning the appropriate state plane system (ex. NAD_1983_HARN_StatePlane_Colorado_Central_FIPS_0502_Feet) and then applying an affine processor that defines a ground adjustment factor and horizontal and vertical offset as A0 and B0 values respectively. Example shown in 1. ORD GCS Setting.png. In this example the data was truncated by 2 million units X and 1 million Y with a GAF of 1.00048188. This works great for CAD! The issue is that when I export the data to a SHP, it goes with a .prj file that ArcGIS can't recognize (2.Topo.txt - changed to txt for upload, normally a .prj). I think ArcGIS can only recognize basic projections and not projections with affine modifiers.

So I need a way to define an affine transformation in ArcGIS, either to the basemap or data being brought in. I thought I could do with a .wld3. I found this article that shows a similar workflow to define a transformation with a raster but can't get my data to use it. World files for raster datasets—ArcGIS Pro | Documentation

Any help would be greatly appreciated. Also, I am new here so if there's a better place to post this inquiry please let me know.

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DGN to GIS with Affine Processor