[Qgis-user] Rasterize vector

[Carlos Cerdán]

El 23/10/12 12:49, David J. Bakeman escribió:
> On 10/23/2012 10:10 AM, Luciano La Sala wrote:
>> Dear QGIS experts,
>>
>> I am using QGIS V. 1.8.0. and I have a shapefile of Argentina which I need
>> to convert to raster. I looks as a pretty straightforward process, but along
>> the way I hit the following problem:
>>
>> 1) Once the vector file is loaded, I go to Raster >> Conversion >> Rasterize
>> (Vector to raster)
>> 2) I select the output file but the following message pops up: "The output
>> file doesn't exist. You must set up the output size to create it."
>> 3) I hit Ok and then I am left to decide what size do I want for the output
>> file. The default values are Width = 3000 and Height = 3000.
>>
>> So at this point my questions are:
>>
>> a) What are these values for width and height? What do they represent? After
>> conversion, I load the raster and under properties and metadata tab it says
>> that dimensions of raster are X: 3000 Y: 3000 Bands: 1, but I am not sure
>> what this means.
> Those values represent the number of pixels in the X and Y direction.
>
> So if your original vector file represents 10km by 10km then each pixel
> represents 3.33333m.
Yes, it is. Those dimensions are the number of columns and rows 
respectively that will be asigned to the new raster map to be created.
The more value, the more resolution that you get, but also the more size.

If you are working with a DEM or another raster map (Landsat perhaps) 
then use that resolution as reference.

Carlos Cerdán