Note: This addon document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade your GRASS GIS installation, and read the current addon manual page.
The min options specifies the minimum number of points to be used for interpolation. If the number of input points is smaller than or equal to the minimum number of points, global TPS interpolation is used. If the number of input points is larger than the minimum number of points, tiled local TPS interpolation is used. Tile sizes are variable and dependent on the extents of the min nearest neighbors when a new tile is generated.
The smooth option can be used to reduce the influence of the splines and increase the influence of the covariables. Without covariables, the resulting surface will be smoother. With covariables and a large smooting value, the resulting surface will be mainly determined by the multiple regression component.
The overlap option controls how much tiles are overlapping when the min option is smaller than the numer of input points. Tiling artefacts occur with low values for the min option and the overlap option. Increasing both options will reduce tiling artefacts but processing will take more time. Values for the overlap option must be between 0 and 1.
The module works best with evenly spaced sparse points. In case of highly unevenly spaced points, e.g. remote sensing data with gaps due to cloud cover, the thin option should be used in order to avoid tiling artefacts, otherwise a high number of minimum points and a large overlap value are required, slowing down the module.
The memory option controls only how much memory should be used for the covariables and the intermediate output. The input points are always completely loaded to memory.
g.region -p rast=elev_state_500m
v.surf.tps input=precip_30ynormals_3d output=precip_30ynormals_3d \ column=annual min=140
v.surf.tps input=precip_30ynormals_3d output=precip_30ynormals_3d \ column=annual min=140 covars=elev_state_500m
v.surf.tps input=precip_30ynormals_3d output=precip_30ynormals_3d \ column=annual min=140 covars=elev_state_500m smooth=0.1
v.surf.tps input=precip_30ynormals_3d output=precip_30ynormals_3d \ column=annual min=20 covars=elev_state_500m smooth=0.1 \ overlap=0.1
Precipitation computed based on annual normals and elevation as a covariable
Available at: v.surf.tps source code (history)
Latest change: Mon Jun 28 07:54:09 2021 in commit: 1cfc0af029a35a5d6c7dae5ca7204d0eb85dbc55
Note: This addon document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade your GRASS GIS installation, and read the current addon manual page.
Main index | Vector index | Topics index | Keywords index | Graphical index | Full index
© 2003-2023 GRASS Development Team, GRASS GIS 7.8.8dev Reference Manual