Thank you very much for your work and the provided code!
I tried to run the C++ Renderer but encountered some problems when rendering higher LODs.
I am using Windows 10 / Libtorch 1.8 / CUDA 11.1 with a GeForce RTX 3090.

I had to make some changes to get the code running, especially changing some datatypes (e.g. from long to uint64_t). All the changes can be seen here coledea@9f2cebf.
Additionally I had to set g_TargetLevel to something smaller than g_SPC.getLevel() (e.g. 5). Otherwise I would get an illegal memory access error.
After that, the code compiled and I was able to run the application.

I trained on the armadillo model and I am able to render the neural representation with the provided python tools. With the C++ renderer, however, I am only able to render the lower LODs. On higher LODs, parts of the model are missing (as the pictures show) or I get the error CUDA Error: invalid configuration argument and nothing is rendered at all.

When activating debug output it shows for example a negative number for #elem in cf level 3:

offset_ on cf level 3 : 5122
# elem in cf level 3 : -1570503101
offset on parent nuggets array 4: 63
# elem in parent nuggets array 4: 156
offset on nuggets array 5 : 219
# elem in nuggets level 5 : 590

Lowest LOD.

Lowest LOD + 2

Lowest LOD + 3

Have you ever encountered this sort of problem and do you maybe know how to fix this?

EDIT: Interestingly, I am able to render higher LODs when using the model provided in #5. After clicking repeatedly +, I then get again the CUDA error (invalid configuration argument). I am using this .npz file: link