GiD_Raster create|interpolate|subsample|fillnodatavalue
To create from the mesh a raster (2D grid) with a value that represents the z, and use a raster to efficiently interpolate values to other points or all points of other raster.
A raster is defined with a Tcl list of the following data:
<ncols> <nrows> <xllcenter> <yllcenter> <xcellsize> <ycellsize> <nodata_value> <values>
ncols, nrows are the number of columns and rows of values (representing values on center of cells)
xllcenter,yllcenter are the x,y coordinates of the lower-left corner
xcellsize, ycellsize are the x,y sizes of the cells, usually the same value (compulsory to be exported as ArcInfo grid ASCII)
<nodata_value> is the special value to represent that the data doesn't exists (usually -9999.0 for ArcInfo grid ASCII)
<values> is an objarray of (ncols x nrows) doubles with the scalar value to be represented, usually the z of the x,y node.
GiD_Raster create {nodes <xyz_nodes>} ?{<cellsize>}{<ncols> <nrows>}|{<ncols> <nrows> <xllcenter> <yllcenter> <xcellsize> <ycellsize> <nodata_value>}?
To create a raster from a cloud of 3D nodes
<xyz> must be an objarray of doubles with "x1 y1 z1 ... xn yn zn" values of a cloud of coordinates.
z data will be extrapolated to grid with and averaged value of the near nodes
GiD_Raster create {nodes <xyz_nodes>}
The raster will be created with automatic number of rows, columns and limits
GiD_Raster create {nodes <xyz_nodes>} {<cellsize>}
The raster will be created with the specified cell size, equal for x and y, and automatic number of columns, rows, and limits
GiD_Raster create {nodes <xyz_nodes>} {<ncols> <nrows>}
The raster will be created with the specified number of columns and rows, and automatic limits
GiD_Raster create {nodes <xyz_nodes>} {<ncols> <nrows> <xllcenter> <yllcenter> <xcellsize> <ycellsize><nodata_value>}
The raster will be created with the specified number of columns and rows, lower-left center, cell sizes and no data value.
GiD_Raster create {triangles <xyz_nodes> <elements>} ?{<cellsize>}{ncols nrows}|{ncols nrows <xllcenter> <yllcenter> <xcellsize> <ycellsize> <nodata_value>}?
To create a raster from a irregular mesh of 3D triangles
<xyz> must be an objarray of doubles with "x1 y1 z1 ... xn yn zn" values of a the node's coordinates.
<elements> must be an objarray of integers with the index (starting by 1) or the 3 nodes of each triangle. "t1_1 t1_2 t1_3 .. tn_1 tn_2 tn_3"
z data will be extrapolated to grid finding the triangle that contain the coordinate in 2D projection, or a near node.
GiD_Raster create {triangles <xyz_nodes> <elements>}
The raster will be created with automatic number of rows, columns and limits
GiD_Raster create {triangles <xyz_nodes> <elements>} {<cellsize>}
The raster will be created with the specified cell size, equal for x and y, and automatic number of columns, rows, and limits
GiD_Raster create {triangles <xyz_nodes> <elements>} {<ncols> <nrows>}
The raster will be created with the specified number of columns and rows, and automatic limits
GiD_Raster create {triangles <xyz_nodes> <elements>} {<ncols> <nrows> <xllcenter> <yllcenter> <xcellsize> <ycellsize> <nodata_value>}
The raster will be created with the specified number of columns and rows, lower-left center, cell sizes and no data value.
GiD_Raster interpolate ?-closest? <raster_interpolation> {nodes <xy_nodes>}|{raster <raster_to_interpolate_without_data>}
To use <raster_interpolation> to calculate interpolated values of a collection of 2D nodes or all grid nodes of another raster
It returns and obj_array of doubles with the interpolated value for each node
<xy_nodes> list of x y coordinates "x1 y1 ... xn yn" of the points to interpolate the value
<raster_to_interpolate_without_data> another raster (its values could be a emtpy empty objarray)
If -closest flag is set, then instead interpolate it get the value of the closest grid node (interesting to map non-continous continuous integer values)
GiD_Raster subsample <raster> <increment_row> ?<increment_col>?
It returns a new raster subsampling the input raster jumping columns and row by increment_row and increment_col
increment_row must be an integer>0 and <num_rows of the input raster
If increment_col is omitted it is assumed equal to increment_row
GiD_Raster fillnodatavalue<raster>
To fill the missing values (with nodata special value) interpolating them from the existing values. The raster itself is modified.
Some auxiliary Tcl procedures:
GIS::GetRasterFromTriangles { {cellsize 0.0} }selected_element_ids cellsize far_points_set_nodata far_points_distance }
It returns a raster from the current selected mesh of triangles.selected_element_ids is expected sorted increasing.
If cellsize is not specified an 0.0an automatic value is used
far_points_set_nodata 0 or 1
GIS::GetRasterFromNodes { {cellsize 0.0} }selected_node_ids cellsize far_points_set_nodata far_points_distance }
It returns a raster from the current selected mesh nodes. selected_node_ids is expected sorted increasing.
If cellsize is not specified 0.0 an automatic value is usedGIS::SubsampleRaster { raster increment show_advance_bar }
It returns a new raster subsampling the input raster jumping columns and row by increment
show_advance_bar must be 1 to show and advancing bar during the process far_points_set_nodata 0 or 1
if 0 all grid points will have interpolated value, 1 far grid points will be set with special nodata (usually -9999) value
far_points_distance is only used if far_points_set_nodata is 1, and must be a distance>=0.0 (if 0.0 will use an automatic distance value)
GIS::ImportRaster_Geometry { raster show_advance_bar {value_smoothed_to_nodes 1} }
It creates geometrical surfaces (and its lines and points) from the raster
values are considered on elements (the value on the cell center), and the mesh created will connect these centers.
but with value_smoothed_to_nodes==1 they are calculated on the nodes, averaging the value of the cells to be a continuous field.
GIS::CreateSurfaceParallelLines { raster {layer ""} }
It creates a single NURBS surface interpolating a collection of near-parallel curves (that interpolate the points of each row of the raster).
<layer> is the layer where the new surface will be assigned (the current layer to use if defaulted to "")
GIS::ImportRaster_Mesh { raster show_advance_bar {value_smoothed_to_nodes 1} {pre_post "pre"}}
It creates mesh quadrilaterals (and its nodes) from the raster. p
re_post can be "post" to create mesh of postprocess.
GIS::SaveRaster_ArcInfoASCII { raster filename }
It saves the raster in the file named filename with ArcInfo grid ASCII format
GDAL::ReadRaster { filename show_advance_bar }
It return a raster with from the file named filename.
The format could be some raster geospatial data format allowed by the GDAL (Geospatial Data Abstraction Library).
Some of them are: ArcInfo, geotiff, png, jpg, and much more.