2

The stripes rotate as zoom level changes

Is there an option to stop this effect?

  • could you please supply more information about your raster: file format, CRS, resolution, settings, zoom levels with issues... – Victor Sep 27 '16 at 8:13
  • It is a vegetation index in format of .tif, 12cm resolution. – Christina Kallimani Sep 28 '16 at 15:04
2

This is most likely a moire interference pattern caused by regular patterns in the data and the regular pattern in the pixels on your screen - thus the pattern changes depending on zoom.

Building ‘pyramids’ for your raster image should solve the problem, creating appropriate intermediate zoom images. Pyramids don’t affect the values of the base image - they’re simply there to help your GIS display the data more quickly and, in this case, accurately.

Open up the layer properties and select 'pyramids':

enter image description here

Select (using shift for multiple selections) all the zoom levels in the list on the right. Select an appropriate resampling method - 'gauss' seems to work well for most rasters I've worked with, but experiment:

enter image description here

After clicking OK it may take a little while depending on the size of the raster, but afterwards you'll be able to zoom without the moire effects appearing.

This persists for the current project only as far as I know, unless you choose 'internal' pyramids - however, that runs the risk of damaging your original raster file (which I have seen happen!).

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2

It's probably down to the resampling of the rows of vegetation. You can try changing the resampling method of your raster, or even halt it altogether

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