Computational region: Difference between revisions
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The current region or computational region is the actual setting of the region boundaries and the actual raster resolution. | <p>The current region or computational region is the actual setting of the region boundaries and the actual raster resolution. | ||
</p><p>As a general rule in GRASS: | |||
As a general rule in GRASS: | </p> | ||
<ol><li> Raster maps are always <b>imported completely</b> at their own resolution (exception: WMS imported layers). | |||
</li><li> In computations, raster <b>input</b> maps are automatically cropped/padded and rescaled (using nearest-neighbour resampling) to match the current region in order to produce the output raster map or to query values. | |||
</li><li> Raster <b>output</b> maps have their bounds and resolution equal to those of the current computational region. | |||
</li></ol> | |||
<h3> FAQs </h3> | |||
<p><b>Q:</b> I don't see anything! | |||
</p><p><b>A:</b> Typically the computational region is set to an area not covering the raster map of interest. Use <span class="fck_mw_template">{{cmd|g.region}}</span> to adjust the computational region settings, e.g. by setting it to the raster map: | |||
</p> | |||
<pre class="_fck_mw_lspace"> g.region rast=myrastermap -p | |||
</pre> | |||
<p><br /> | |||
<b>Q:</b> The raster map looks ugly. | |||
</p><p><b>A:</b> The resolution of the computational region does not match the resolution of the raster map. Use <span class="fck_mw_template">{{cmd|g.region}}</span> to adjust the resolution settings of the computational region or set it to the raster map (see above). | |||
</p><a _fcknotitle="true" href="Category:FAQ">FAQ</a> | |||
Revision as of 20:57, 23 October 2011
The current region or computational region is the actual setting of the region boundaries and the actual raster resolution.
As a general rule in GRASS:
- Raster maps are always imported completely at their own resolution (exception: WMS imported layers).
- In computations, raster input maps are automatically cropped/padded and rescaled (using nearest-neighbour resampling) to match the current region in order to produce the output raster map or to query values.
- Raster output maps have their bounds and resolution equal to those of the current computational region.
FAQs
Q: I don't see anything!
A: Typically the computational region is set to an area not covering the raster map of interest. Use g.region to adjust the computational region settings, e.g. by setting it to the raster map:
g.region rast=myrastermap -p
Q: The raster map looks ugly.
A: The resolution of the computational region does not match the resolution of the raster map. Use g.region to adjust the resolution settings of the computational region or set it to the raster map (see above).
<a _fcknotitle="true" href="Category:FAQ">FAQ</a>