Hi Awe,

The extraction of Landsat pixel values is not a GIS process. Hence I would not advise to use GIS software to perform pixel extraction, but on the contrary use remote sensing image processing software. There are many free and licensed software packages around on the internet offered by specialists in remote sensing image processing and especially LANDSAT has much standard software which has been developed to perform this job. Remote Sensing is not GIS and vice versa. Hence the algorithms used in remote sensing are different from those in GIS.

I can recommend ENVI as a good software package especially to extract information from LANDSAT imagery.

If you prefer like to stick to SAGA GIS to avoid the learning curve in RS image processing, it will cost you much more time to obtain quantitatively exact results with GIS software and secondly you run the risk that your LANDSAT imagery will remain a SAGA as well.

So take the fast lane, by learning and using remote sensing software. You will start enjoying it after having stepped the learning curve a bit.

Cheers,

Frank

Hi Awe,

I assume that you did not execute the module completely. If you execute interactive tools in SAGA GIS, they are started but they require other actions from you. Therefore you have to choose the black "Action" arrow in the top area of your user interface. Once this "Action" arrow is activated you can manually choose points from your grid in the Map view. The chosen points/values are stored in the newly created table in your Data Tree. When you have finished your selection you have to stop the module execution manually again, by clicking on the executed module.

Hope this helps you in your further SAGA GIS actions.

Greetings,

Fabian

Hi Awe,

Landsat images, like any other raster image, can be handled quite smoothly in most GIS software. No need to learn special remote sensing software if you do not plan to use such data on a day-to-day basis.

To extract pixel values from any raster image in SAGA GIS, just use the module you suggested (Geoprocessing>Grid>Values>Grid value Request (interactive)). Once you select a pixel in the image, the corresponding value is stored in a new table named "Grid Values". When you are finished, stop the module by selecting it again. If you want to generate a list of pixels, just select Options-Method-Collect values when executing the module. Also make sure you have the newest SAGA version, for it is updated regularly.

Cheers,

Thomas

Hi Awe,

I had the same problem as you. I think I have a solution that could help:

Geoprocessing >> File >> Grid >> Export >> Export Grid to XYZ

Only works to images stored in hard disk. I tried with a dem in *.sgrd format and with other morphometric images created from de dem

The module is fast and Creates a file *.xyz that can be opened with excel. Select by location. In ArcMap you can create xy events with those values because you get column X and column Y. The Z column has the values you want

JPM Castro

If help is still needed, please talk with my soil physics/erosion group while you are at UFSM.