I have a raster in Quantum GIS and I am just exploring it. How can I see average of raster value over certain area, marked by mouse? In other words:

  1. How can I select particular area in QGIS?
  2. How can I compute average of raster value over that area?

You should try Zonal Statistics plugin.

enter image description here

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  • thank you. What about the question 1, i.e. pure area selection? This must be very simple, but I am new to QGIS. – Tomas Jul 12 '13 at 17:57
  • create a polygon – SS_Rebelious Jul 13 '13 at 17:33
  • There's no simpler way of making a rectangle selection? Even MS Paint can do this :-) – Tomas Jul 15 '13 at 9:36
  • It is quite simple. More 'simpler' way will require custom tool. QGIS is open-source. You can create and add any tool you need on your own. So go ahead and create one ))) – SS_Rebelious Jul 15 '13 at 14:17
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    Look more carefully. I have it. See updated answer. – SS_Rebelious Jul 21 '13 at 16:26

The select tool can be seen here. If you click on the drop down you can change the method used to select (rectangle, freehand etc): enter image description here

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  • this won't help as the select tool is for vector layers only – Curlew Jan 3 '14 at 11:07
  • for the raster sure, but if he were to vectorise the data it would be a handy tool for a 'rectangle selection' i think? – Rob Lodge Jan 3 '14 at 11:52
  • Then edit your answer to point out all the steps. But note that the question is over 5months old and the OP probably already found a solution – Curlew Jan 3 '14 at 12:26

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