Hello Tim: I looked at you process and there doesn't seem to be anything wrong with it. I think the issue is with the heights (elevations) obtained from the photos. I have used drones to acquire images but I use conventional aircraft with on board cameras and gps units for the majority of my work. Most drones have gps units on them which is where the camera gets its XYZ position; however unless you have an expensive drone (+$25K an above) the positions you get are not super accurate +- 5-8metres. In addition the elevations from these gps units are measured above the WGS84 ellipsoid and can't be changed The gps units that I use in the aircraft allow us to change the vertical reference and get geoidal elevations which are in effect elevations above sea level or orthometric elevations In other words the camera elevations generally match the elevations (height) from the aircraft altimeter. Most engineering and construction projects require orthometric elevations which I suspect is what you want. The following link explains these different types of elevations http://www.gistutor.com/concepts/9-beginner-concept-tutorials/19-explaining-the-differences-between-ellipsoids-geoids-and-topographic-elevation.html Depending on where you are in the world the difference between an ellipsoidal and geoidal elevation can be significant. The following link is a calculator for these differences https://www.unavco.org/software/geodetic-utilities/geoid-height-calculator/geoid-height-calculator.html If you go to the Reconstruction that you created and look at the spatial tab, does the elevation range generally match what you want? Also if you open your production in the CC Viewer and measure a point, is the elevation correct? What happens if you change the Spatial Reference system in the viewer to output orthometric heights do you get the values that you want? It seem to me that you need to adjust your model to get orthometric heights; you may be able to use Advanced tab to change the origin but I am not sure if this will work I don't use ConceptStation so I cannot comment on how you can adjust the elevations in this application. I use ESRI GIS and Autodesk products and these allows me to modify the elevations Sorry to be so long winded but it's not an straightforward solution. Using control points accurately measured by a surveyor in the field is the sure way to get everything to line up Farouk Rohoman
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