“Put on a map” by using Approximated nearest neighbor in image processing

Question

I used python to read a hdf file(Hierarchical Data Format) that contains image data from a satellite(the name should be MODIS). The python code is able to get the longitude, the latitude and radiance of the image. Then use the data to produce an image.

My teacher told me the objective is to put the image on the map, which I don't understand the meaning of this. But she mentioned to "put" the image on the map, I most likely have to use the "Approximated Nearest neighbor" Library ( ANN library).

After the image is "put" on the map, it should look like this:

So what is the meaning of "Put" the image on the map? Thank you.

Answer 1

I assume it means you have to take an image of a map and display your data (radiance) on top of it.

The difficulty is that the pixels of your map image will not correspond to your data points, so you will have to interpolate your data at each pixel of your map image. Nearest neighbor is one way to do it.

Basically what you have to do is for a given pixel of your image, find its location in the coordinates of your data (latitude and longitude) and find the data point nearest to this point and save its radiance. Do this for each pixel and you obtain an image of the same size as your map image that you can superimpose as in the example image you showed.