log depth interpolation not handled correctly for large geometries

Our “big” geometries aren’t tessellated enough for log depth to interpolate correctly right now, which causes issues that look kind of like near-plane problems but don’t present as a planar cut:

On Sandcastle

I’m pretty sure it’s the “minimum tessellation” problem (described here: http://outerra.blogspot.sk/2009/08/logarithmic-z-buffer.html) because adding #define ENABLE_GL_POSITION_LOG_DEPTH_AT_HEIGHT to the top of vertexLogDepth.glsl seems to fix the problem.

[cesium-concierge]

Congratulations on closing the issue! I found these Cesium forum links in the comments above:

https://groups.google.com/d/topic/cesium-dev/kMZIgIa6lqQ/discussion https://groups.google.com/forum/#!topic/cesium-dev/NZwZnQnmC2U https://groups.google.com/forum/#!topic/cesium-dev/WhCZhIUaJIQ https://groups.google.com/d/msg/cesium-dev/hsPdXyBATS4/zNF17JkFCAAJ https://groups.google.com/d/msg/cesium-dev/fXHvE2psXD4/t181NoF1AgAJ

If this issue affects any of these threads, please post a comment like the following:

The issue at https://github.com/CesiumGS/cesium/issues/6573 has just been closed and may resolve your issue. Look for the change in the next stable release of Cesium or get it now in the master branch on GitHub https://github.com/AnalyticalGraphicsInc/cesium.

[OmarShehata]

Came up again here: https://groups.google.com/d/msg/cesium-dev/fXHvE2psXD4/t181NoF1AgAJ