4 Cool Features in CVAT to Know About!

Andhika S Pratama
Data Folks Indonesia
4 min readNov 27, 2022

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This edited image is taken from https://cvat.org

Some of you may have heard of this annotation tool called CVAT. But what is CVAT for those who don’t know? CVAT or Computer Vision Annotation Tools is a free image annotation tool. It can also be used to annotate video too in which the tool will take the duration of the video into several frames.

With that being said, after handling several projects of polygonal annotations I find these four features to be very useful for us when polygonal bound images or videos that some of you may not know!

Here are some of the features that I find very useful for polygonal bounding:

  1. Select any layer regardless of the order
Select any layers regardless of the order of creation

This may not seem to be a “cool” feature but there are some tools that cannot let you select any layers freely so you can only select the latest layer of the bounding box or polygons. Having this feature makes it easier to just delete any layer, and select or move any layer that you want without having to delete, hide or move the top layer first (labelimg for example needs you to do this).

So yeah, it is pretty cool.

2. Follow existing points in polygonal annotation

Following existing point

This feature is pretty helpful especially when you have entities that are interjected with each other. This feature makes you easily create points as you can just follow the ones that you have created for the other entity.

This feature also saves you a lot of time because the amount of effort is sliced by half as you can just left-click on the first point from the existing point, and then on to the second one. Once the second point becomes purple, then you can choose which points you want to follow onwards. You can only follow the points created from one entity only. As you can see in the example, I only follow the points from one entity.

If I want to follow the next entity points, then I have to finish following the first one and then I can just do the same thing for the next entity that I want to follow (I hope you understand this as it is a little difficult to explain unless you try it yourself).

3. Toggle annotation markings on/off

Marking toggle on/off

This is a simple feature in CVAT but I believe not many people know how to do this. Once you have a lot of polygons in one image, if you want to start drawing a new one you will see a lot of dots from the polygons you have drawn.

This can be very annoying especially if you want to create whole new polygons without even touching the points of the existing polygons (see the previous feature). Also, if you feel uncomfortable seeing a lot of points then this feature really helps you minimize the feeling.

You can do this by simply pressing CTRL on your keyboard in annotation mode.

4. Redraw from existing points in polygonal annotation

Redrawing the polygons

This is my number one favorite feature in CVAT hands down for polygonal bounding. You can easily redraw your polygon from whatever points you desire. By pressing Shift on your keyboard (outside the annotation mode) after you choose the points that you want to start redrawing (as you can see in the example) then you can start drawing the new path for the bounded entity.

The reason why this feature is one the best is because imagined if this feature is not supported and somehow you want to cover more areas of the entity (when doing some quality checks for example) or if you accidentally press (N) in your keyboard that closes the polygon. You will need to delete the entire polygon and spend a lot of time redrawing from 0.

These features here are actually in the official GitHub of CVAT under the “screencast” section (lol) but some of us may not have the time to watch through all of the video tutorials provided and just go into the annotation tools straight away (I know this because I figured out these features by myself after doing several projects and not knowing there is a tutorial for such features provided by CVAT)

If you want to look more for what kind of features that the CVAT provided other than these, then you can go to the CVAT GitHub page and look under the “screencast” section.

Hopefully, this article is useful to you guys for your annotation projects using CVAT. Let me know what you think about this feature in the comment section!

See you in the next article! bye bye!

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Andhika S Pratama
Data Folks Indonesia

Hi there! Currently, I’m a Data Annotator in Tictag.io who have an interest in writing such as Copywriting, and UX Writing.