GMS:Rasters: Difference between revisions

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{{Template:Version GMS 9.0}}
{{Template:Version GMS 9.0}}


DEMs (digital elevation models), and [[GMS:Images|images]] that include elevation data such as a [http://trac.osgeo.org/geotiff/ GeoTIFF], are referred to as "rasters". Using the third-party software [http://www.bluemarblegeo.com/global-mapper/ Global Mapper], GMS supports a large number of DEM formats. DEMs are imported and displayed as images. Thus they are only displayed in plan view and are not true 3D surfaces like a TIN. The raster icon [[image:raster.png]] is different from the image icon [[image:image.png]] to indicate it includes elevation data. Rasters don't have to be DEMs. For example, the values at the pixels can represent concentrations, or flow rates ... or anything.
DEMs (digital elevation models), and [[GMS:Images|images]] that include elevation data such as a [http://trac.osgeo.org/geotiff/ GeoTIFF], are referred to as "rasters". Using the third-party software [http://www.bluemarblegeo.com/global-mapper/ Global Mapper], GMS supports a large number of DEM formats. After importing, DEMs are listed under "GIS Data" in the Project Explorer along with other images. The raster icon [[image:raster.png]] is different from the image icon [[image:image.png]] to indicate it includes elevation data. Rasters don't have to be DEMs. For example, the values at the pixels can represent concentrations, or flow rates ... or anything.


==Importing DEMs==
==Importing DEMs==
DEMs can be imported by simply opening the file(s) or dragging and dropping the file(s) into the GMS window.
DEMs can be imported by simply opening the file(s) or dragging and dropping the file(s) into the GMS window. Multiple files can be imported at once.


==Creating rasters==
==Creating rasters==
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==Interpolating from rasters==
==Interpolating from rasters==
Rasters can be interpolated to most other objects, including the z values of [[GMS:Feature_Objects|feature objects]] and to [[GMS:Interpolate_to_MODFLOW_Layers|MODFLOW layers]]. The interpolation is done by finding the raster cells that the object's points are in and assigning the points the values from the raster cells.
Rasters can be interpolated to most other objects, including the z values of [[GMS:Feature_Objects|feature objects]] and to [[GMS:Interpolate_to_MODFLOW_Layers|MODFLOW layers]]. The interpolation is done by finding the raster cells that the object's points are in and assigning to the points the values from the raster cells.


==Conversion from rasters==
==Conversion from rasters==
Rasters can be converted to a [[GMS:2D_Grid_Module|2D grid]] or [[GMS:2D_Scatter_Point_Module|2D scatter points]].
Rasters can be converted to a [[GMS:2D_Grid_Module|2D grid]] or [[GMS:2D_Scatter_Point_Module|2D scatter points]].
==Raster display options==
==Raster display options==
The GIS tab of the [[GMS:Display_Options|Display Options]] dialog is used to change the way rasters are displayed. The only options currently available are the shader, which controls the color ramp, and whether to enable hill shading (shadows). These options are from Global Mapper.
The GIS tab of the [[GMS:Display_Options|Display Options]] dialog is used to change the way rasters are displayed. DEMs are imported and displayed as either 2D images or as a 3D point cloud.
 
 
 
===Display as 2D image===
 
If displaying as a 2D image, the raster is only visible in plan view (like other images). This option is fast and memory efficient and can support large rasters (or several rasters). Hill shading, which enables shadows and thus makes the image appear 3D, is available in this mode.
 
 
 
===Display as 3D points===
 
If displaying as 3D points, the raster is visible in any view, not just plan view. 3D points are also very memory efficient but may be a little slower than the 2D image option. Also, hill shading is not available in this mode. The point size and the maximum number of points to display can be specified. Specifying a maximum number of points can be useful if the size of the raster is such that rendering becomes slow.
 
 
 
===Shaders===


With either 2D or 3D, four different shaders, which control the color ramp, are available. A color legend can be displayed to relate colors with values.


{{Navbox GMS}}
{{Navbox GMS}}
[[Category:Feature Objects]]
[[Category:Feature Objects]]
[[Category:GMS General Information]]
[[Category:GMS General Information]]

Revision as of 16:13, 25 September 2012


DEMs (digital elevation models), and images that include elevation data such as a GeoTIFF, are referred to as "rasters". Using the third-party software Global Mapper, GMS supports a large number of DEM formats. After importing, DEMs are listed under "GIS Data" in the Project Explorer along with other images. The raster icon Raster.png is different from the image icon File:Image.png to indicate it includes elevation data. Rasters don't have to be DEMs. For example, the values at the pixels can represent concentrations, or flow rates ... or anything.

Importing DEMs

DEMs can be imported by simply opening the file(s) or dragging and dropping the file(s) into the GMS window. Multiple files can be imported at once.

Creating rasters

Rasters can be created from within GMS by interpolating from 2D scatter points. The interpolation options, the raster cell size, and the extents of the raster can all be specified in the Scatter -> Raster dialog.

Interpolating from rasters

Rasters can be interpolated to most other objects, including the z values of feature objects and to MODFLOW layers. The interpolation is done by finding the raster cells that the object's points are in and assigning to the points the values from the raster cells.

Conversion from rasters

Rasters can be converted to a 2D grid or 2D scatter points.

Raster display options

The GIS tab of the Display Options dialog is used to change the way rasters are displayed. DEMs are imported and displayed as either 2D images or as a 3D point cloud.


Display as 2D image

If displaying as a 2D image, the raster is only visible in plan view (like other images). This option is fast and memory efficient and can support large rasters (or several rasters). Hill shading, which enables shadows and thus makes the image appear 3D, is available in this mode.


Display as 3D points

If displaying as 3D points, the raster is visible in any view, not just plan view. 3D points are also very memory efficient but may be a little slower than the 2D image option. Also, hill shading is not available in this mode. The point size and the maximum number of points to display can be specified. Specifying a maximum number of points can be useful if the size of the raster is such that rendering becomes slow.


Shaders

With either 2D or 3D, four different shaders, which control the color ramp, are available. A color legend can be displayed to relate colors with values.