AIS visualization TASK

Introduction

• 

  The map and some coordinates

• 

  The map shall be transformed to photo

The position of vessels on a photo.

Data acquisition

USE RTL-AIS, ship162 (https://github.com/xoolive/ship162) project and Python, with tape measure antenna.

Or GNU AIS saves the data to local MySQL server.

Transform

Some ideas to generate the transformation. Full camera projection is not needed here.

The latitude/longitude scale is not a linear measure. Thus, to a conversion to metric scale is better. UTM projection (pyproj) or using a local tangent plane. The UTM projection works better for this 10-20 km distances.

Homology

https://docs.opencv.org/4.x/d9/dab/tutorial_homography.html

The simplest; ${\begin{bmatrix}u\\v\\1\end{bmatrix}}{\tilde {=}}H{\begin{bmatrix}x\\y\\1\end{bmatrix}}$

Should have some 10-50 corresponding pairs to get the mapping correct. Use least squares or SVD, but OpenCV works with RANSAC.

Non rigid spatial warp

Thin plate spline, $(u,v)=f(x,y)$ where $f(x,y)=a_{1}+a_{2}x+a_{3}z+\sum _{i}w_{i}U(|p-p_{i}|)$ and $U(r)=r^{2}\log r$