GiD_Raster create|interpolate

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 <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 objarray)

Some auxiliary Tcl procedures:

GIS::GetRasterFromTriangles { {cellsize 0.0} }

It returns a raster from the current mesh of triangles. If cellsize is not specified an automatic value is used

GIS::GetRasterFromNodes { {cellsize 0.0} }

It returns a raster from the current mesh nodes. If cellsize is not specified an automatic value is used

GIS::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

GIS::ImportRaster_Geometry { raster show_advance_bar }

It creates geometrical surfaces (and its lines and points) from the raster

GIS::ImportRaster_Mesh { raster show_advance_bar }

It creates mesh quadrilaterals (and its nodes) from the raster

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.