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Digitising cliff surface features in 3D?

Question asked by james.sturman on Mar 17, 2016

I have been given a number of photos of a near vertical cliff surface with features (points and polygons/areas) hand drawn on them and I have been asked to digitise the features so that they can be represented in a 3D model. I have LiDAR terrain data for the cliff and some aerial photography that I can use for spatial reference. I also have the ArcGIS 3D software platform that includes ArcScene, ArcGIS Pro and City Engine.

 

Ideally I'd like to be able to wrap the photos onto the near vertical Lidar terrain and then digitise the features using standard editing tools. Is there a standard method for stitching together a series of photos and draping them across a vertical cliff face in Arc?

 

With regard to digitising the features I can easily drop points on the near vertical surface, but digitising areas/polygons is far more difficult. When I add new vertices they don't always fall where I click and jump up or down depending on the LiDAR terrain. Also, I'd like the resulting polygon to be draped on the cliff surface like a multipatch feature, which is not how the resulting polygons look.

 

I have had some success using 2D polygons and the Interpolate Polygon to Multipatch tool, but this was for larger areas of the cliff face and I'm now looking at digitising much smaller areas.

 

Another option I have considered is rotating the vertical cliff (LiDAR points or TIN or Multipatch), digitising the areas in ArcMap (2D), running the Interpolate Polygon to Multipatch tool and then rotating the results back into the vertical position. However, my initial attempts at rotating a multipatch feature representing the cliff weren't particularly successful.

 

If anyone has any experience with this type of thing or has any suggestions let me know. Also, for reference I have been doing much of this in ArcScene, but I do have access to ArcPro too.

 

Thanks

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