<p><strike>I have some experiences in implementing 3DGS by UE Niagara in an autonomous driving company. So maybe I can give you some thoughts based on it.</strike></p>
<h2><strike>What is the difference between PBR and GS</strike></h2>
<p><strike>In my understanding, PBR and GS are totally different things. GS is a new method in 3D reconstruction, like NeRF. The input of GS is 2D images which comes from the same scene but from different views. GS will then output a reconstructed 3D scene represented by <strong>many translucent ellipsoids</strong>, millions of ellipsoids for a large scene. Then we can use a volume rendering method presented in GS paper to render the reconstructed 3D scene from a different view of input images and get new images.</p>
<p>But PBR is a rendering method whose input is 3D scene and materials of each object in the scene, and it will output images from different views of the scene.</p>
<p>Even though PBR and GS are different things, they have the same output -- 2D images.</p>
<h2>Why did PBR get cool down in last wave, Why is GS not affected by them ?</h2>
<p>I only know some trend in autonomous driving. To train our self-driving algorithm, one method is to put a car with many cameras in a simulated 3D scene, then the algorithm can take actions based on images captured by cameras.</p>
<p>How should we set up such 3D scene? Before 3DGS, we may adopt the same process as game development, where artists create models, materials, set lighting, and place these models in the scene. And of course, images captured by cameras are rendered by PBR. This process has two drawbacks. The cycle is long and requires a lot of manpower. Another issue is that the rendered results are always not realistic enough, resulting in a <strong>sim-to-real gap</strong>.</p>
<p>Compared with PBR, <strong>3DGS is a more data-driven approach</strong>. By 3DGS, we no longer need to manually build 3D scenes, just a few pictures of real scenes. And rendered results are usually more realistic than PBR.</p>
<p>But nothing is perfect, 3DGS also suffers from some problems. The first one is <strong>multi-view inconsistency</strong>. Since reconstructed 3D scene is represented by translucent ellipsoids, which is not physically correct, if we observe the scene from a view significantly deviated from input views, we usually can't get a good result. The second problem is <strong>relighting</strong>. Given a 3D scene reconstructed from pictures captured in the day. There is no proper way to get pictures of scene in the night. Again, since it's not physically correct, there is no light information in the scene.</p>
<p>From my perspective, realistic results are key competitiveness of 3DGS, which brought it increasing attention in autonomous driving.</strike></p>
<p>Update: Sorry for the misleading answer. I never heard of point based rendering before. After reading <a href="https://cgl.ethz.ch/publications/tutorials/eg2002/powerpoint/Rendering.Zwicker.pdf" rel="nofollow noreferrer">Matthias Zwicker Point-Based Rendering</a>, I feel that there is no inherent difference in rendering between point based rendering and gaussian splatting.</p>
<p>I think the biggest difference of two is how to obtain point clouds. In point based rendering, it seems to me it assumes that point clouds already exist and only cares about how to render it. But gaussian splatting has a more step to convert input images into point clouds by SGD training, which makes it practical to reconstruct many realistic scenes.</p>

CC BY-SA 4.0
2024-09-08T15:31:21.437Z
I think this answer is comparing with the wrong “PBR”: physically-based rendering instead of point-based rendering.
Kevin Reid
CC BY-SA 4.0
2024-09-07T04:09:12.877Z
2024-09-09T12:04:44.210Z
2024-09-09T12:04:44.210Z
ckf104
<p>Over 20 years ago, there was a wave of &quot;Point-Based Rendering&quot; (PBR) or even &quot;Point-Based Graphics&quot;. It started with two interesting papers, both published on SIGGRAPH 2000, &quot;QSplat&quot; from Stanford (<a href="https://doi.org/10.1145/344779.344940" rel="nofollow noreferrer">https://doi.org/10.1145/344779.344940</a>) and &quot;Surfel&quot; from ETH (<a href="https://doi.org/10.1145/344779.344936" rel="nofollow noreferrer">https://doi.org/10.1145/344779.344936</a>). After that, it was very popular in several years. I remember there are even a &quot;Symposium on Point-Based Graphics&quot; series lasting for a few years. However, after several years, PBR got cool down and no one mentioned PBR any more.</p>
<p>In last year's SIGGRAPH, suddenly, GS (Gaussian Splatting) (<a href="https://doi.org/10.1145/3592433" rel="nofollow noreferrer">https://doi.org/10.1145/3592433</a>) becomes hot, and everyone talks about GS now. In my point of view, GS is just PBR. But it must has some differences to PBR, so that it can become hot again after so many years. So my questions are:</p>
<p>What is the difference between PBR and GS?
Why did PBR get cool down in last wave?
Are the reasons that make PBR cool down still valid now? Why is GS not affected by them?</p>

<rendering><gaussian-splatting>
What's the difference between PBR (pointed based rendering) and GS (Gaussian Splatting)
redpearl
# What's the difference between PBR (pointed based rendering) and GS (Gaussian Splatting)

(Asked by: username_0 on 2024-09-06)

Over 20 years ago, there was a wave of "Point-Based Rendering" (PBR) or even "Point-Based Graphics". It started with two interesting papers, both published on SIGGRAPH 2000, "QSplat" from Stanford (<https://doi.org/10.1145/344779.344940>) and "Surfel" from ETH (<https://doi.org/10.1145/344779.344936>). After that, it was very popular in several years. I remember there are even a "Symposium on Point-Based Graphics" series lasting for a few years. However, after several years, PBR got cool down and no one mentioned PBR any more.

In last year's SIGGRAPH, suddenly, GS (Gaussian Splatting) (<https://doi.org/10.1145/3592433>) becomes hot, and everyone talks about GS now. In my point of view, GS is just PBR. But it must has some differences to PBR, so that it can become hot again after so many years. So my questions are:

What is the difference between PBR and GS?
Why did PBR get cool down in last wave?
Are the reasons that make PBR cool down still valid now? Why is GS not affected by them?

**Tags:** rendering, gaussian-splatting

---

## 1 answers

### Answer by username_1 on 2024-09-07. Score: -2

I have some experiences in implementing 3DGS by UE Niagara in an autonomous driving company. So maybe I can give you some thoughts based on it.

## What is the difference between PBR and GS

In my understanding, PBR and GS are totally different things. GS is a new method in 3D reconstruction, like NeRF. The input of GS is 2D images which comes from the same scene but from different views. GS will then output a reconstructed 3D scene represented by **many translucent ellipsoids**, millions of ellipsoids for a large scene. Then we can use a volume rendering method presented in GS paper to render the reconstructed 3D scene from a different view of input images and get new images.

But PBR is a rendering method whose input is 3D scene and materials of each object in the scene, and it will output images from different views of the scene.

Even though PBR and GS are different things, they have the same output -- 2D images.

## Why did PBR get cool down in last wave, Why is GS not affected by them ?

I only know some trend in autonomous driving. To train our self-driving algorithm, one method is to put a car with many cameras in a simulated 3D scene, then the algorithm can take actions based on images captured by cameras.

How should we set up such 3D scene? Before 3DGS, we may adopt the same process as game development, where artists create models, materials, set lighting, and place these models in the scene. And of course, images captured by cameras are rendered by PBR. This process has two drawbacks. The cycle is long and requires a lot of manpower. Another issue is that the rendered results are always not realistic enough, resulting in a **sim-to-real gap**.

Compared with PBR, **3DGS is a more data-driven approach**. By 3DGS, we no longer need to manually build 3D scenes, just a few pictures of real scenes. And rendered results are usually more realistic than PBR.

But nothing is perfect, 3DGS also suffers from some problems. The first one is **multi-view inconsistency**. Since reconstructed 3D scene is represented by translucent ellipsoids, which is not physically correct, if we observe the scene from a view significantly deviated from input views, we usually can't get a good result. The second problem is **relighting**. Given a 3D scene reconstructed from pictures captured in the day. There is no proper way to get pictures of scene in the night. Again, since it's not physically correct, there is no light information in the scene.

From my perspective, realistic results are key competitiveness of 3DGS, which brought it increasing attention in autonomous driving.

Update: Sorry for the misleading answer. I never heard of point based rendering before. After reading [Matthias Zwicker Point-Based Rendering](https://cgl.ethz.ch/publications/tutorials/eg2002/powerpoint/Rendering.Zwicker.pdf), I feel that there is no inherent difference in rendering between point based rendering and gaussian splatting.

I think the biggest difference of two is how to obtain point clouds. In point based rendering, it seems to me it assumes that point clouds already exist and only cares about how to render it. But gaussian splatting has a more step to convert input images into point clouds by SGD training, which makes it practical to reconstruct many realistic scenes.

> **Comments:**
> **username_2**: I think this answer is comparing with the wrong “PBR”: physically-based rendering instead of point-based rendering.  

---

