Add SDFStudio links (#1653)

Add sdf studio links

docs/extensions/sdfstudio.md

@@ -0,0 +1,50 @@
+# SDFStudio
+
+[project website](https://autonomousvision.github.io/sdfstudio/)
+
+```{image} imgs/sdfstudio_overview.svg
+:width: 800
+:align: center
+:alt: sdfstudio overview figure
+```
+
+## Overview
+
+SDFStudio is built on top of nerfstudio. It implements multiple implicit surface reconstruction methods including:
+
+- UniSurf
+- VolSDF
+- NeuS
+- MonoSDF
+- Mono-UniSurf
+- Mono-NeuS
+- Geo-NeuS
+- Geo-UniSurf
+- Geo-VolSDF
+- NeuS-acc
+- NeuS-facto
+- NeuralReconW
+
+You can learn more about these methods [here](https://github.com/autonomousvision/sdfstudio/blob/master/docs/sdfstudio-methods.md#Methods)
+
+## Surface models in nerfstudio
+
+We intend to integrate many of the SDFStudio improvments back into the nerstudio core repository.
+
+Supported methods:
+
+- NeuS
+
+## Citation
+
+If you use these surface based models in your research, you should consider citing the authors of SDFStudio,
+
+```none
+@misc{Yu2022SDFStudio,
+    author    = {Yu, Zehao and Chen, Anpei and Antic, Bozidar and Peng, Songyou Peng and Bhattacharyya, Apratim
+                 and Niemeyer, Michael and Tang, Siyu and Sattler, Torsten and Geiger, Andreas},
+    title     = {SDFStudio: A Unified Framework for Surface Reconstruction},
+    year      = {2022},
+    url       = {https://github.com/autonomousvision/sdfstudio},
+}
+```

docs/index.md

@@ -60,6 +60,7 @@ Contributing<reference/contributing>
 :caption: Extensions
 extensions/blender_addon
 extensions/unreal_engine
+extensions/sdfstudio
 ```
 
 ```{toctree}