---
# System prepended metadata

title: Cloud Compare
tags: [Computer Vision]

---

# Cloud Compare
## What's cloud compare
CloudCompare is a point cloud registration / interrogation tool and it also allows you to do other useful operations like subsampling to reduce size and do quick visualisations and animations.
## How to start?
* [Cloud Compare Downlad Link](http://www.danielgm.net/cc/release/)

## How to merge multiple Objs in one?
### - Align：
#### Method：Picking (equivalent) point pairs
Document：[Align - Picking (equivalent) point pairs](https://www.cloudcompare.org/doc/wiki/index.php?title=Align)

1. Import multiple .Obj files.
2. Choose multiple entities from DB Tree. (Press Ctrl to select multiple entities)
3. Press "Align" button![](https://i.imgur.com/JtgKhYc.jpg) and select aligned entities (the one actually moving at the end)
4. Pick point pairs (you must have picked exactly the same number of points in each cloud and picked at least 3 equivalent point pairs in both entities.)
5. Press "Align" button to preview the result.
6. Press "Check Mark" to save the result.

![](https://i.imgur.com/FE4TOD8.png)


#### Method：Auto-align(Not Recomment)
1. Choose multiple entities from DB Tree. (Press Ctrl to select multiple entities)
2. Select 'Tools > Sand box (research) > Auto align clouds' menu entry.
![](https://i.imgur.com/oO7NgND.png)


### - Automatic registration：
This tool can automatically finely registers two entities (clouds and/or meshes).

Document：[ICP](https://www.cloudcompare.org/doc/wiki/index.php?title=ICP)
1. Choose multiple entities from DB Tree. (Press Ctrl to select multiple entities)
2. Press Finely Register![](https://i.imgur.com/25PU59y.jpg)
3. Choose which entity will be the 'Aligned' one (Registered, will eventually move) and which one will be the 'Reference' one (Reference, won't move). 

![](https://i.imgur.com/v74syGz.png)

**Main parameters**
* **Number of iterations/RMS difference**: ICP is an iterative process. During this process, the registration error (slowly) decrease. We can tell CC to stop this process either after a maximum number of iterations, or as soon as the error (RMS) difference between two iterations becomes lower than a given threshold. The smaller this threshold is, the longer it will take to converge, but the finer the result should be (note: as CC work with 32 bits floating point values, a 1e-8 threshold is already near the computation accuracy limit and it shouldn't be necessary to go any lower).

* **Final overlap**: this is a new parameter for the version 2.6.1. It lets the user specify the actual portion of the data/registered cloud that would actually overlap the model/reference cloud if both clouds were registered. This let the user register entities with only a partial overlap (down to 10% or even less).

* **Adjust scale**: the modified-ICP algorithm we use is able to determine a potential difference in scaling. If your clouds have different scales (e.g. photogrammetry clouds) you can check this option so as to resolve the scaling as well.

Renferce：
[Document](chrome-extension://oemmndcbldboiebfnladdacbdfmadadm/https://www.danielgm.net/cc/doc/qCC/Documentation_CloudCompare_version_2_1_eng.pdf)
[Cloud Compare wiki](https://www.cloudcompare.org/doc/wiki/index.php?title=Main_Page)

###### tags: `Computer Vision`
