I have calculated Normalised Difference Vegetation Index using Landsat 8 data, but don't know how to assign/extract geographic information. Can someone help me to resolve this one?
If i understood your question well you need to change your UTM coordinates to Geographic coordinates.
Best wishes
Geographic coordinates are already assigned to Landsat 8 and derived products. Depending on which RS/GIS tool you use, there are multiple ways to identify and extract pixel value/location information. I have attached a screenshot which shows two ways. The tools are highlighted with red rectangular boxes.
1. In ENVI there are tools which directly provides you the pixel value along with their location information. E.g., 'Cursor Value', 'Crosshairs', and with 'Region of Interest (ROI)' tool you can extract these values.
2. In ArcMap try the 'Identify' tool.
I agree with Mr. James, if you have used Landsat 8 data to calculate NDVI then it is automatically geo-referenced.
Thank you for your valuable response. How can I perform the same thing in python?
Again, there are many different ways to achieve this using Python scripts. A quick search on the web revealed multiple ways. I have attached a link that I found useful. For that you need to Install the GDAL package in Python. Alternatively, In my example, I ran Arcpy within Python Window of ArcMap to extract the pixel value of a particular coordinate. It makes use of the ArcToolbox - 'Data Management Tools > Raster > Raster Properties > Get Cell Value'. Following is the executable code (font in bold italics) and the result can be viewed in the python result window. Check the attached screenshot for directions.
>>> import arcpy
>>> result = arcpy.GetCellValue_management ("ndvi", "365401.027 3782561.433", "")
https://gis.stackexchange.com/questions/225370/get-individual-pixel-values-on-a-raster-image-using-gdal-and-python
If you have the intrested coordinate points, then you can extract by multiple points on arcgis.
You only have to change your coordinates to shapefiles then extract the NDVI values on it.
I want a set of latitude / longitude associated with each pixel. How one can perform this in Python?
Answer to this question is available here:
https://github.com/cayetanobv/raster2xyz/blob/master/test/runtest.py
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