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 Photogrammetry - Create Deliverables - Elevation Raster option greyed out

Tiffany Finke's profile image
Tiffany Finke posted 08-03-2023 11:30

Hello,

When creating deliverables from the Photogrammetry tab in TBC, if the Elevation Type is set to Digital Surface Model, the Elevation Raster option is greyed out.  If I switch to Digital Terrain Model as the Elevation Type the Elevation Raster option becomes active and I can check the box to create an Elevation Raster.  Previously, I was able to create a DSM, but not any longer.  I have version 5.9 installed and just updated with the 5.9.1 patch. Has anyone else had this issue?  

Thomas Widmer's profile image
Thomas Widmer posted 08-08-2023 13:17

Hello Tiffany Finke,

v5.90 did include two different DSM algorithms. They were named DSM and DSM HQ. The DSM HQ runs a pixel-based matching algorithm, allowing to create true-orthomosaics. We enhanced the speed and performance, getting similar processing times as with the DSM method from v5.90. Therefore we removed the DSM method from v.5.90 and kept going on with the DSM HQ method from v5.90 as the point cloud was of supirior quality and it provided a true-orthomosaic. For naming simplicity, we "renamed" the DSM HQ to DSM in v5.90.1.

If you want to create a raster, we recommend using the DTM algorithm. You can run it on high quality and set your raster density as you need. The raster is an interpolated result, which is a generalized representation of an existing point cloud. It is mainly used for terrain representation and therefore mainly used with the DTM approach.

Are you not satisfied with the raster result from the DTM approach? Please let us know more details, to understand your case.

Tiffany Finke's profile image
Tiffany Finke posted 08-09-2023 11:55

Hi Thomas,

Thank you for the response.  I'm still not quite clear on why I am unable to create a DSM as in your explanation you state that the DSM HQ was renamed to DSM in v5.90.1. This makes me think that I should have that option since I'm using that version of TBC. 

I see that you recommend the DTM for raster but what if my stakeholder wants a DSM?  Do I now have to export to a different platform like ArcGIS to create the DSM from the point cloud?  

Thomas Widmer's profile image
Thomas Widmer posted 08-10-2023 08:37

Hi Tiffany Finke,

is your stakeholder asking you for a raster TIFF from the DSM process? Is the raster result from the DTM approach not sufficient?

Creating a raster from a true-ortho point cloud (which is created in the DSM approach) will cause much confusion. The main issue is that the raster cannot "catch" all the objects which have been part of the DSM point cloud and therefore be very disturbed. Therefore we removed it, as people started to compare the raster with the original DSM point cloud, which of course does not match to each other.

Please let me understand why this feature would be important. Is there a use case that are allowed to share and let us know?

Hope we can find a way to solve this.