Update Instant-NGP & Density Grid with CUDA supports. Much faster and better PSNR. (#193)

README.md

@@ -60,7 +60,7 @@ pip install -e .
 # Install library with CUDA support. Change setup.py to `USE_CUDA = True` and then
 python setup.py develop
 
-# Install tiny-cuda-nn (tcnn) to use with the graph_instant_ngp.yaml config
+# Install tiny-cuda-nn (tcnn) and apex to use with the graph_instant_ngp.yaml config
 pip install git+https://github.com/NVlabs/tiny-cuda-nn/#subdirectory=bindings/torch
 
 # Run the test cases