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Add a height above ellipsoid setting for RTK photos.

JamesBurton1

I would like a height above ellipsoid setting when setting up a new project. Our RTK photos reference ellipsoid height, but I would like our 3D products to output in orthometric/geoid heights. They come out at the correct height when using ground control, but I don't want to have to do ground control on every job, especially when the RTK looks so good already. Adjusting the height after processing is not a complete solution, and is not possible on all the products. Then if you publish those layers, you have to do that height adjustment again in AGOL. I want my products at the correct height for 3D scenes after processing.

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Comments

MarkBarker1

Hi @JamesBurton1 ,

When are you initially adding the imagery to the new project page what coordinate systems are you defining for the image coordinate system?

Assuming this is the same project you were posting about in the other community post, then you are currently accepting the default of GCS: WGS_1984/VCS: EGM96 Geoid. Your RTK drone is likely collecting in a specific vertical ellipsoidal coordinate system, so the first step before you do anything else would be to make sure that you are defining both horizontal and vertical image coordinate systems correctly.

Once the image coordinate system is defined, you would then define the project coordinate systems. Drone2Map will automatically apply a transformation when processing, so products go from the image coordinate system to this project coordinate system.

The difference between your RTK image vertical coordinate system (ellipsoidal) and the project vertical coordinate system (orthometric) is the height above ellipsoid. So, if you are seeing the offsets as you mention that would be the first thing to review.

Are you able to provide a processing report from a project processed without ground control?

Regards,

Mark

JamesBurton1

Hey @MarkBarker1,

Appreciate the reply, can't attach a PDF in an idea post. I am working with several projects at this point which were flown with RTK corrections from the State of Utah CORS network (TURN). I have processed my data using the default GCS (WGS_1984) and VCS (EGM96 Geoid). I am trying to output my data in PCS:NAD 1983 (2011) State Plane Utah Central Meters and VCS:NAVD88 Height (meters). I continually get an output that is 17 m, give or take, below the orthometric web scenes. I've stopped using the Fixed Images for RTK since it didn't appear to work, and it appears that would force my data to have an offset by using the ellipsoid height.

Beyond that configuration, I have tested other GCS and VCS like the TURN networks (NAD83 (2011)) to try and use an ellipsoidal VCS instead of the EGM96 Geoid. Keep getting this negative vertical offset unless I use ground control.

Feel free to follow up outside this thread.

James Burton

jburton@msd.utah.gov

JamesBurton1

This Idea is no longer needed. The solution to the ellipsoid to geoid projection not working is the following link. You must have the ArcGIS Coordinate System Data program installed. https://community.esri.com/t5/arcgis-drone2map-questions/rtk-ellipsoid-height-to-orthometric-geoid-height/m-p/1328360#M1382