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Barely started using QGIS last week so I'm still pretty confused with the nodata and burn parameter in raster conversion tool. I tried reading other people's question in this forum and through YouTube (all are previous versions) but I'm still pulling blanks, all I do get are:

  1. Nodata and burn value shouldn't be the same;
  2. Burn means giving the pixels value;
  3. Nodata kind of reads the pixel value;
  4. I tried doing random combinations of nodata and burn value like is shown in the picture, for example burn = 500 and nodata = 0, burn = 500 and nodata = -999, burn = 1 and nodata 0. Some really random numbers basically. But their differences aren't much different with each other so I got confused on which to use. So ultimately I'm curious on how others decide what values they put in in their nodata and burn parameter when they're trying to rasterize a vector to get the best results they wanted

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So I guess you are looking for the definition of the terms burn & nodata. What is important to note is that raster layers are always rectangular in shape, but some pixels can be invisible (="nodata"). In your example all the area of the raster layer outside of the bus stop buffer is filled with nodata pixels. In some cases it makes sense to assign a specific value to the nodata pixels (for instance if you want to further process the raster layer with other rasters that already have specific nodata values).

Burn value: the value the pixels of the raster should have that actually contains data. If it is assigned every pixel that contains data (=the extents of the bus stop buffer in your case) has the burn value. Again, something that can be useful for further analysis, but might not be needed in this case.

Hope this clarifies it for you!

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  • Ah i see, so we decide the what the value is for a pixel to be invisible with nodata. But what about burn? The value the pixels of the raster "should have" that actually contains data. How can i decide what value to burn in the pixels?
    – Oisif
    Commented Nov 23, 2020 at 3:29
  • That really depends on what you need the raster for. The only time I use the burn value is to create a mask layer and then I assign it the value 1 to make calculations easy. Otherwise there is also the option to assign a burn in value from one of the vector fields (the option above the set burn value in the dialog) , then each raster pixel takes the value of that field at that location. Commented Nov 23, 2020 at 10:19

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