How to generate ORBvoc.txt?

[liubamboo]

Thanks for your great work. I want to know how to create ORBvoc.txt. I want to generate ORBvoc.txt independently. Could you help me?

[Gautham-JS]

Hello there,

ORBvoc.txt is essentially a database of previously seen feature descriptors stored in a formatted file for fast place recognition for triggering loop closure instead of matching features one by one against all images.This type of place recognition is done using a hierarchical tree to create a bag of words representation of the image feature space.

This vocabulary is generated by using DBoW2. You can read the paper at http://doriangalvez.com/papers/GalvezTRO12.pdf . In this repo, ./demo shows a minimal example on creating vocabulary files.

In the context of SLAM and Loop closure detection with it, This will be helpful.

Also DBoW2 generates the vocabulary file in .yaml format and saves it as .yml.gz format. but like you asked ORB SLAM2 uses .txt file, thats because the DBoW2 version provided with ORB SLAM2 in ./Thirdparty folder is slightly modified to support .txt files. check out the source here.

Hope it helps. G.

[SnowCarter]

Hi, I can't find the ./demo folder. Could you please check it again?

[Gautham-JS]

Hey @SnowCarter , The ./demo folder i was refrencing to is from the original repo for DBoW2 : https://github.com/dorian3d/DBoW2

[SnowCarter]

Great, thank you.

[SnowCarter]

Please forgive my stupid question. If I create a vocabulary by using DBOW3. Can I apply it here (DBOW2)?

[DanyPell]

@SnowCarter I do wonder if it would be better to use DBoW3, or FBoW (which DBoW3 repo says it's better): https://github.com/rmsalinas/fbow