How Accurate are Google Photorealistic 3D Tiles Altitudes?

3D Tiles
1

Hello! As the title says - I’m wondering how accurate the geometry and altitudes of the Google Photorealistic Tiles data set are supposed to be?

I ask because I’m visualizing the Google Photorealistic Tiles dataset using 3DTilesRendererJS for three.js and am seeing some discrepancies in the expected altitudes. The peak of Mt Everest, for example, is supposed to measure at 8,849 m but the height only seems to reach to 8,700 m. Here is a screenshot of the two altitudes relative to the Mt Everest peak. The green, 20 meter diameter ball is at 8,849 m and the red one is at 8,700 m:

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The altitude is derived by computing the distance to the surface point on the WGS8 which is computed using a function based on Cesium’s implementation.

Thank you!

2

It looks like there’s a significant offset in Google Earth, as well. Hovering over the Mt Everest pin shows that it’s well over 100 m off of the 8,849 m altitude, as well. The differences in altitude between the renderers may be some discrepancies in how WGS84 altitude is calculated but this seems to be a data issue?

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