Documentation for k-planes add-on (#1935)

* Add documentation for kplanes add-on

* Fix all integration spots with nerfstudio

---------

Co-authored-by: gmeanti <giacomo.meanti@gmail.com>

docs/index.md

@@ -112,6 +112,7 @@ This documentation is organized into 3 parts:
 ### Third-party Methods
 
 - [Instruct-NeRF2NeRF](nerfology/methods/in2n.md): Editing 3D Scenes with Instructions
+- [K-Planes](nerfology/methods/kplanes.md): Unified 3D and 4D Radiance Fields
 - [LERF](nerfology/methods/lerf.md): Language Embedded Radiance Fields
 - [Tetra-NeRF](nerfology/methods/tetranerf.md): Representing Neural Radiance Fields Using Tetrahedra
 

docs/nerfology/methods/index.md

@@ -28,6 +28,7 @@ The following methods are supported in nerfstudio:
     :maxdepth: 1
     Instant-NGP<instant_ngp.md>
     Instruct-NeRF2NeRF<in2n.md>
+    K-Planes<kplanes.md>
     LERF<lerf.md>
     Mip-NeRF<mipnerf.md>
     NeRF<nerf.md>

docs/nerfology/methods/kplanes.md

@@ -0,0 +1,87 @@
+# K-Planes
+
+<h4>Explicit Radiance Fields in Space, Time, and Appearance</h4>
+
+
+```{button-link} https://sarafridov.github.io/K-Planes/
+:color: primary
+:outline:
+Paper Website
+```
+
+```{button-link} https://github.com/sarafridov/K-Plane
+:color: primary
+:outline:
+Official Code
+```
+
+```{button-link} https://github.com/Giodiro/kplanes_nerfstudio
+:color: primary
+:outline:
+Nerfstudio add-on code
+```
+
+<video id="teaser" muted autoplay playsinline loop controls width="100%">
+    <source id="mp4" src="https://sarafridov.github.io/K-Planes/assets/small_teaser.mp4" type="video/mp4">
+</video>
+
+**A unified model for static, dynamic and variable appearance NeRFs.**
+
+
+## Installation
+
+First, install nerfstudio and its dependencies. Then install the K-Planes add-on
+```
+pip install kplanes-nerfstudio
+```
+
+## Running K-Planes
+
+There are two default configurations provided which use the blender and DNeRF dataloaders. However, you can easily extend them to create a new configuration for different datasets.
+
+The default configurations provided are
+| Method            | Description              | Scene type                     | Memory |
+| ----------------- | -------------------------| ------------------------------ | ------ |
+| `kplanes`         | Tuned for blender scenes | static, synthetic              | ~4GB   |
+| `kplanes-dynamic` | Tuned for DNeRF dataset  | dynamic (monocular), synthetic | ~5GB   |
+
+
+for training with these two configurations you should run
+```bash
+ns-train kplanes --data <data-folder>
+```
+or
+```bash
+ns-train kplanes-dynamic --data <data-folder>
+```
+
+:::{admonition} Note
+:class: warning
+
+`kplanes` is set up to use blender data, (download it running `ns-download-data blender`), 
+`kplanes-dynamic` is set up to use DNeRF data, (download it running `ns-download-data dnerf`).
+:::
+
+
+## Method
+
+![method overview](https://sarafridov.github.io/K-Planes/assets/intro_figure.jpg)<br>
+K-planes represents a scene in k dimensions -- where k can be 3 for static 3-dimensional scenes or 4 for scenes which change in time -- 
+using k-choose-2 planes (or grids). After ray-sampling, the querying the field at a certain position consists in querying each plane (with interpolation), and combining the resulting features through multiplication.
+This factorization of space and time keeps memory usage low, and is very flexible in the kinds of priors and regularizers that can be added.<br>
+<br>
+
+We support hybrid models with a small MLP (left) and fully explicit models (right), through the `linear_decoder` [configuration key](https://github.com/Giodiro/kplanes_nerfstudio/blob/db4130605159dadaf180228be5d0335d2c4d21f9/kplanes/kplanes.py#L87)
+<br>
+<video id="4d_dynamic_mlp" muted autoplay playsinline loop controls width="48%">
+    <source id="mp4" src="https://sarafridov.github.io/K-Planes/assets/dynerf/small_salmon_path_mlp.mp4" type="video/mp4">
+</video>
+<video id="4d_dynamic_linear" muted autoplay playsinline loop controls width="48%">
+    <source id="mp4" src="https://sarafridov.github.io/K-Planes/assets/dynerf/small_salmon_path_linear.mp4" type="video/mp4">
+</video>
+
+The model also supports decomposing a scene into its space and time components. For more information on how to do this see the [official code repo](https://github.com/sarafridov/K-Plane)
+<br>
+<video id="4d_spacetime"  muted autoplay playsinline loop controls width="96%">
+    <source id="mp4" src="https://sarafridov.github.io/K-Planes/assets/dynerf/small_cutbeef_spacetime_mlp.mp4" type="video/mp4">
+</video>

nerfstudio/configs/external_methods.py

@@ -58,6 +58,21 @@ To enable Instruct-NeRF2NeRF, you must install it first by running:
     )
 )
 
+# K-Planes
+external_methods.append(
+    ExternalMethod(
+        """[bold yellow]K-Planes[/bold yellow]
+For more information visit https://docs.nerf.studio/en/latest/nerfology/methods/kplanes.html
+
+To enable K-Planes, you must install it first by running:
+  [grey]pip install kplanes-nerfstudio[/grey]""",
+        configurations=[
+            ("kplanes", "K-Planes model tuned to static blender scenes"),
+            ("kplanes-dynamic", "K-Planes model tuned to dynamic DNeRF scenes"),
+        ],
+        pip_package="kplanes-nerfstudio",
+    )
+)
 
 # LERF
 external_methods.append(