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How to convert my points into a raster along the z attribute and a resolution of 5 minutes or 10 km

First I import the data as a .txt file and then I convert to a vector (shapefile). then I do: Raster> Conversion> rasterise (vector to raster). but the problem in the attribute fields I not find the z column, only the x, y coordinates. I do not know why?

x   y   z
2.88334 42.8458 350169
2.96667 42.8458 350169
2.88334 42.9292 352666
2.96667 42.9292 352666
3.05000 42.9292 352666
2.88334 43.0125 352666
2.96667 43.0125 352666
3.05000 43.0125 352666
2.80000 43.0958 353292
2.88334 43.0958 353292
2.96667 43.0958 352666
3.05000 43.0958 352666
2.80000 43.1792 353292
2.88334 43.1792 353292
2.96667 43.1792 352666
3.05000 43.1792 352666
3.13334 43.1792 353292
2.80000 43.2625 353292
2.88334 43.2625 353292
2.96667 43.2625 353292
3.05000 43.2625 353292
3.13334 43.2625 353292
3.21667 43.2625 353292
3.30000 43.2625 353293
2.71667 43.3458 353292
2.80000 43.3458 353292
2.88334 43.3458 353292
2.96667 43.3458 353292
3.05000 43.3458 353292
3.13334 43.3458 353293
3.21667 43.3458 353293
3.30000 43.3458 353918
3.38334 43.3458 353918
3.46667 43.3458 353918
3.55000 43.3458 353918
2.71667 43.4292 353292
2.80000 43.4292 353292
2.88334 43.4292 353293
2.96667 43.4292 353293
3.05000 43.4292 353293
3.13334 43.4292 353293
3.21667 43.4292 353293
3.30000 43.4292 353918
3.38334 43.4292 353918
3.46667 43.4292 353918
3.55000 43.4292 353918
3.63334 43.4292 353918
3.71667 43.4292 353918
2.80000 43.5125 353293
2.88334 43.5125 353293
2.96667 43.5125 353293
3.05000 43.5125 353293
3.13334 43.5125 353293
3.21667 43.5125 353293
3.30000 43.5125 353918
3.38334 43.5125 353918
3.46667 43.5125 353918
3.55000 43.5125 353918
3.63334 43.5125 353918
3.71667 43.5125 355171
3.80000 43.5125 355171
3.88334 43.5125 355171
2.88334 43.5958 353293
2.96667 43.5958 353293
3.05000 43.5958 353293
3.13334 43.5958 353293
3.21667 43.5958 353918
3.30000 43.5958 353918
3.38334 43.5958 353918
3.46667 43.5958 353918
3.55000 43.5958 353918
3.63334 43.5958 353918
3.71667 43.5958 355171
3.80000 43.5958 355171
3.88334 43.5958 355171
3.96667 43.5958 355171
2.96667 43.6792 353293
3.05000 43.6792 353293
3.13334 43.6792 353293
3.21667 43.6792 353293
3.30000 43.6792 353918
3.38334 43.6792 353918
3.46667 43.6792 353918
3.55000 43.6792 353918
3.63334 43.6792 353918
3.71667 43.6792 355171
3.80000 43.6792 355171
3.88334 43.6792 355171
3.96667 43.6792 355171
3.05000 43.7625 353293
3.13334 43.7625 353293
3.21667 43.7625 353293
3.30000 43.7625 353918
3.38334 43.7625 353918
3.46667 43.7625 353918
3.55000 43.7625 353918
3.63334 43.7625 353918
3.71667 43.7625 355171
3.80000 43.7625 355171
3.88334 43.7625 355171
3.96667 43.7625 355797
4.05000 43.7625 355797
3.13334 43.8458 353293
3.21667 43.8458 353293
3.30000 43.8458 353918
3.38334 43.8458 353918
3.46667 43.8458 353918
3.55000 43.8458 353918
3.63334 43.8458 353918
3.71667 43.8458 353918
3.80000 43.8458 353918
3.88334 43.8458 355797
3.96667 43.8458 355797
3.38334 43.9292 353918
3.46667 43.9292 353918
3.55000 43.9292 353918
3.63334 43.9292 353918
3.71667 43.9292 353918
3.80000 43.9292 353918
3.88334 43.9292 355797
3.46667 44.0125 353918
3.55000 44.0125 353918
3.63334 44.0125 353918
3.71667 44.0125 353918
3.80000 44.0125 355797
3.63334 44.0958 353918
  • It is not very clear what you ask, but I suppose you want to interpolate your values to obtain a z value raster. First of all you need to import your points in QGIS, with the tool "Add delimited text layer" (I assume your points are stored in CSV or TXT file). In the prompt window you have to specified that the coordinates are stored as DMS. Then you can use the raster interpolation, where you can specify the raster cell size as 5 minutes. – Vale Apr 15 '16 at 12:59
  • I do not want to interpolate between points, just convert these points into raster : First I import the data as a .txt file and then I converte to a vector (shapefile). then I do: Raster> Conversion> rasterise (vector to raster). but the problem in the attribute fields I not find the z column, only the x, y coordinates. I do not know why? – tazrart Apr 15 '16 at 15:01
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You could to use "Raster Interpolation" (in Raster menu). Add your data using "Add Delimited Text Layer". (Menu Layer >> Add Layer >> Add Delimited Text Layer.

In Raster Interpolation you could to use Interpolation Method (TIN or IDW), and you could adjust the Cellsize.

| improve this answer | |
4

I think the attribute field must be the type Real with a precision of atleast 1. After you saved your points as a shapefile, create a new field using the Field Calculator:

Field Calculator

And save it. You should have an attribute table like this:

Attribute table

The new field should now be available for rasterizing:

Field available

| improve this answer | |
  • Thank Joseph for your answer, effective I find the "new_z" column with real number. But when I add new_z column as the attribute field, in the end I find a raster all black with a 0 value, normally, I will find a several pixel with different values, and when the values are identical, we see a kind of polygon, which are highly differentiated in color. – tazrart Apr 15 '16 at 15:40

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