Hi everyone, I am writing to ask which method to get 3D coordinates has the best precision. As far as I know, there are at least two functions to get 3D coordinates, scene.pickPositionand scene.globe.Pick, which according to the discussion in here should have different performance. According to the …

[image] qiyanthor: So far, I have tried using the PnP solution for the sanity check, but the results of both functions are very erroneous and just don’t make sense at all. Can you share a Sandcastle example reproducing this issue that we can run? See instructions here: How to share custom San…

Thanks for your message. We actually use the cv2 pakcage in python and I am not sure if a Sandcastle examle could be created for this purpose. The PnP solution could be found here . And the code is pretty straightforward. In theory, one inputs the 2D pixel positions and the corresponding 3D coordina…

Ah, I see. So you’re passing in 2D images, the position of the camera in 3D, and the algorithm is supposed to estimate the camera pose? [image] qiyanthor: The problem is that since the ground-truth of coordinates are unknown I’m curious what you mean by this - since the input data is coming …

Yes exactly! That’s what PnP algorithm does. Since it’s complex to have the ground truth coordinates, we use this for sanity check. And the coordinates from pickPosition and globe.pick lead to quite different PnP results. In this case, do you have any suggestion about how to tell which method is mor…

I think the most accurate result is what you get from sampleTerrainMostDetailed . This takes a longitude/latitude and returns the height at that position. globe.pick will do a ray cast using whatever geometry is currently loaded (so if the terrain you’re raycasting against is very far away the resul…

Thanks for your helpful message. In our design, there are quite many distant pixels (e.g. >2000m away from the camera position), and does the globe.pick have limited performance in such case? We have a good quality terrain models locally stored and it covers a very large area (including those ‘dista…

If you have terrain, the most accurate thing is going to be what is returned from functions like the “sampleTerrainMostDetailed” since that queries the data itself and not what’s rendered on screen/reconstructed from the depth buffer. For 3D Tiles the equivalent is “clampToHeightMostDetailed” as sh…

Thanks for your helpful message!

Precision about different methods to get 3D coordinates

CesiumJS

omar June 8, 2020, 6:15pm 2

Can you share a Sandcastle example reproducing this issue that we can run? See instructions here: How to share custom Sandcastle examples - #3 by omar. I’m curious how you’re evaluating the accuracy here.

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Precision about different methods to get 3D coordinates

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