Generating a Rectangle Grid (DTM)

The rectangle or regular grid is a digital model that shape surfaces through rectangle face polyhedron. Vertexes of those polyhedra can be the sampled points in case they have been acquired in same XY locations that define the wanted grid.


Source: (Spring 5.3, 2012)

The rectangle grid generation must be done when a sampled data in the surface is not obtained with regular spacing. Thus from isoline contained information or in sampled points it is generated a grid that represent as closest as possible to the real surface. Initial values to be determined are x and y coordinate space in a way they can represent close values to the grid points in big variation regions. At same time, they should reduce redundancies in almost plane regions.

The grid space, i.e. x and y resolution, should be ideally lower or equal to the lower distance between two samples in different quotas. When generating a dense grid, with a very small distance between points, there will be a huge amount of information about the analyzed surface, but will need more time to generate. Otherwise considering big distances among points, it will be created a rough grid that could lose information. Therefore, the final grid resolution must have a commitment of data accuracy and grid generation time.

Once defined the resolution and consequently the coordinates in each grid point, it is possible to apply one of interpolation methods to calculate the elevation rounded value.

Select DIGITAL TERRAIN MODEL → GENERATE DTM in the main menu.


Input Layer Name: choose the layer to be processed.

Quota Column: select the column to be used as quota.

Interpolator: select a method from the list.

Power: Weighting power (default 2).

Radius: The radius (X axis if rotation angle is 0) of search ellipse. Set this parameter to zero to use whole point array.

Output Parameters:

Repository: Click on the icon to save the result in a shape file or click on the icon to save it in a data source.

Layer Name: enter the name for the resulting image.

Resolution: enter the values X and Y of pixel size.

Dimension: an alternative is to enter the number of columns (C) and lines (L).

Click on the OK button.