C++ implementation

[sujaygarlanka]

Hello @vaheta and @albertodallolio,

I am Sujay Garlanka. As I was looking into Intrinsic AI to apply to its robotics software engineering opening, I found this repo. After reading the paper and looking through the code, I thought implementing a C++ interface would be a cool opportunity to learn some C++ (this is actually my first C++ project), contribute to open source and understand some of the work done at Intrinsic.

This PR is some of the preliminary work I have done. It is far from complete, however I am putting this PR up to ask some questions I have. I initially used Eigen as the library to deal with all the numpy operations in the python code since this seems to be the default vector/matrix library in C++. However, I am encountering a lot of issues where I have to use for loops to implement vectorized operations in numpy. An alternative is using the tensor class in Eigen, however it is unsupported. I am thinking the best is to use the pytorch tensor library and rewrite the code with that. Before I progress further, I was curious to know what you both recommend. Also, is a C++ interface a useful contribution to this repo?

P.S. Also, this is meant to be a PR for a separate branch, but since no C++ branch exists, just putting it up against main.

Thanks!
Sujay

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[sujaygarlanka]

Hello @vaheta and @albertodallolio,

I implemented the code using the xtensor library because it provided similar functionality to numpy. The CPP implementation closely mimics the python implementation and I validated it by ensuring test.cpp produced the same output as a similar script using the python implementation (Could always use more testing though!). Some additional feedback I am looking for and work remaining is below.

Feedback

• Google C++ style formatting, not sure if this what you want.
• Tried using pass by reference and consts and other CPP best practices, but new to CPP so any advice/feedback here would be really appreciated.
• Also, any syntactic advice on when to use auto for types, usage of namespaces, etc.

Working remaining

• Add ability to accept file paths to point clouds instead of only point clouds (minor addition)
• Build system/CMake for publishing code
• Update INSTRUCTIONS.md and README.md

Thanks!
Sujay