# Frequently asked questions¶

• Compilation fails with the error message: “Error: always_inline function <..> requires target feature <..> but would be inlined into function <..> that is compiled without support for <..>”.

You are likely trying to compile Mitsuba within a virtual machine such as VirtualBox, QEmu, etc. This is not recommended: most of these virtual machines expose “funky” virtualized processors that are missing standard instructions extensions, which breaks compilation. You can work around this issue by completely disabling vectorization at some cost in performance. In this case, add the following line to the top-level CMakeLists.txt file (e.g. in line 4 after the project() declaration).

add_definitions(-DENOKI_DISABLE_VECTORIZATION=1)

• Differentiable rendering fails with the error message “Failed to load Optix library”.

It is likely that the version of OptiX installed on your system is not compatible with the video driver (the two must satisfy version requirements that are detailed on the OptiX website)

• Differentiable rendering fails with an error message similar to “RuntimeError: cuda_malloc(): out of memory!”.

The rendering or autodiff graph exhausted your GPU’s memory. Try reducing the sample count and / or resolution. If high sample count renders are necessary, it is possible to split computation in several low sample count passes and average together the gradients.

• Citing Mitsuba 2 in scientific literature.

Please use the following BibTeX entry to cite Mitsuba 2 in research articles, books, etc.

@article{NimierDavidVicini2019Mitsuba2,
author = {Merlin Nimier-David and Delio Vicini and Tizian Zeltner and Wenzel Jakob},
title = {Mitsuba 2: A Retargetable Forward and Inverse Renderer},
journal = {Transactions on Graphics (Proceedings of SIGGRAPH Asia)},
volume = {38},
number = {6},
year = {2019},
month = dec,
doi = {10.1145/3355089.3356498}
}


Here is a plain-text version of the above:

Merlin Nimier-David, Delio Vicini, Tizian Zeltner, and Wenzel Jakob. 2019. Mitsuba 2: A Retargetable Forward and Inverse Renderer. In Transactions on Graphics (Proceedings of SIGGRAPH Asia) 38(6).

A pre-print of this article is available here.