Hi Sahar,

Coordinates of each grid cell are implicitly incorporated in every projected raster dataset; Typically you'll have coordinates of a point of origin or boundary box, information on the size of each pixel, and numbers of rows/cols. As such, the geographic position and extent of each pixel is fully constrained. Consequently, I find it hard to imagine an usage scenario in which explicit coordinates would provide added value, particularly when considering that you will boost the file size. This is also the reason why you will hardly find a build-in function for this purpose in any GIS software. Instead you will probably have to write a function yourself that walks through the pixels of your dataset, obtains coordinates (of the cell center?), and then appends lat/lon values as values to a new dataset. I don't know ENVI in detail, but I guess this task will be relatively easy to solve in python or R, e.g. look here: https://pcjericks.github.io/py-gdalogr-cookbook/raster_layers.html or here:

https://gis.stackexchange.com/questions/60527/how-to-extract-values-from-rasters-at-location-of-points-in-r

Cheers,

David

Hi David,

Thank you very much for detailed explanation. I would be also very thankful if you could let me know whether you have any information for doing such programming in MATLAB language also or not?

Cheers,

Sahar

I can add the following information about the entire grid information I have in my image data. Please have a look to the attached pictures. There is one matrix which includes latitude information for the entire pixels and a matrix grid with longitude data for each pixel. There is also another matrix (or raster image) with the intensity information.

My image data has the location information in separate matrices.

Hi Sehdar,

I exclusively use free and open software, so I don't work with Matlab, either. However, the basic concept will be the same in Matlab as in python or R; You will just have to figure out the right modules to load and modify the syntax. Mathworks always points out that their outstanding user support is a key reason to spend thousands of Euros for their software, so take them at their word and let their support help you with details on how to write such a program in Matlab :)

Regarding your figures, I'm afraid I do not yet fully comprehend what they show and you want to do. What are the units in the lat and long images km? Certainly no geographic coordinates, which I thought you wanted to use? What are the values on the y-axis? Do you want to extract values from the lat/lon raster at the locations indicated by the marks in the intensity image?

Cheers,

David

Dear David,

Thank you very much for your response.

Finally I found the approach to solve this problem. I have used ENVI software in the Map menu. I think Using the registration of images with Input Geometry (IGM), will solve the problem.

By having a grid of latitude data (in Y axis) and longitude data (in X axis), we can use IGM for building a Geographic Look Up Table (GLT) file easily.

Greetings,

Sahar