Lucas-Kanade flow
[Takeo Kanade](https://texonom.com/takeo-kanade-c58c9360159d471fa9cfb053c9d41444) 


### Limitation
- The motion is larger than a pixel
> - [Coarse to Fine](https://texonom.com/coarse-to-fine-3764c48c535f4505b7d39c291701ed8e) 
>> - find large motion from coarse image
- A point does not move like its neighbor
- Brightness constancy does not hold
![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fd3960c8d-1b44-4f7b-9923-f882a613df62%2FUntitled.png?table=block&id=7d32bcb6-c24a-4460-af37-4d350444a2a0&cache=v2)
[Second Moment Matrix](https://texonom.com/second-moment-matrix-11b24324bf3c480eaa71412dab72369e) 
We can figure out whether the system is solvable by looking at the eigenvalues of thesecond moment matrix



### Limitation
- motion is larger than pixel
> - [Coarse to Fine](https://texonom.com/coarse-to-fine-3764c48c535f4505b7d39c291701ed8e) 
- broken [spatial coherence constraint](https://texonom.com/spatial-coherence-constraint-d02be2bb9da14f29b9f1dc98ad8f8060) 
> - motion segmentation
- [brightness constancy constraint](https://texonom.com/brightness-constancy-constraint-840f53954f294625afd1b8256761d46f) could not hold
> - Exhaustive neighborhood search with normalized correlation







