Presentation Dialog box of the application
Syntax

Presentation

This application takes a vector point file, a line/arc file, a polygon ornode file (whether structured or not) and rasterizes it using an existing ornew raster.

Although the application supports all MiraMon vector formats it isrecommended that structured formats are used in the case of polygon filessince these allow holes within polygons and are free of overlapping polygons(except for any non topological groups that they may contain). Moreover thestructured vector formats allow linking to a database, which in turn allowsa greater degree of control over the raster attributes and the automaticgeneration of categories. If an unstructured polygon files is rasterizedthen where superpositions occur the value of the last polygon prevails.

Based on MiraMon structured vector files, the application supports therasterization of many types of field attributes: Numeric ('N'),Logical ('L'), Character ('C') or Date ('D'). Fornumeric ('N') fields the numeric value is rasterized directly,whilst for logical ('L') fields the raster contains 1 for true and 0for false. In this case TiraVec allows the user to indicate another field(numeric, alphanumeric, date, ...) for defining the raster category.Similarly, if the field for rasterizing is Character ('C') or Date('D') type then the application automatically generates a numericalindex which is rasterized as the raster value and these raster categoriesare documented with their equivalent alphanumeric attributes.
Based on unstructured vectors the application supports "integer"(long), "real" or "string" vector attributes. For"integer" and "real" type attributes only thoseattributes that are, or can be, transformed into numbers are rasterized. For"string" type attributes the application can also automaticallygenerate a numerical index which corresponds to a description of the rastercategories, as described above for structured vectors.

Apart from the different mentioned vector formats, this application also allows the rasterization of a TIN model (Triangulated Irregular Network). In this case, the input file should be a structured polygons file where each polygon must be triangular and every vertex of the polygons must have a Z value. To rasterize this layer, an interpolated Z value will be assigned to every cell from the three vertices of the polygon where the cell is contained.

TiraVec can raster over MiraMon raster files, that is "bit","byte", "integer", "long" and "real"formats, as well as over the compressed formats "byte-RLE","integer-RLE", "long-RLE" and"real-RLE".
Should the numerical value fall outside the range of allowed values for theraster image then it is possible to choose between saturating the maximum orminimum value, or eliminating the value as out of range. The following arethe allowed values for each type of raster, whether RLE type ordecompressed:

In the case of structured polygons the zero polygon (or the universalpolygon that encloses all the rest) is not rasterized.

If the category definition field is set and there already existedpredefined categories then the category definition in the DOC file will be:'Nueva' / 'Vieja' (New/Old). It should be rememberedthat "real" type raster files do no support categories.

In cases where the REL vector file describes the units (REL v4 or above),this is appropriately documented in the documentation of the resultingraster file. If this is not the case, the name of the field used fordefining categories is placed as 'value units' in the DOC file ofthe raster or, if this is not available, the name of the rasterizedfield.

For the case of polygon files there are two basic criteria forrasterization: based on area, based on the central point; and acombination.
The first assigns to the cell the value to the category that occupies mostof its area; this is approximated by examining a horizontal line crossingthe cell. The second criterion simply assigns the value to the cell of thecategory that is found at its centre, without considering the fraction ofthe area of the cell that this category represents.
In the case of a TIN, the criterion of the center point will be used by default.
Sometimes, when we rasterize isolated polygons thinner than a pixel on aNODATA background, any criteria explained before is good enough in the normalmode. In this case, it is useful to combine them with the polygons as apolygons with border mode.

For this latter reason there exists a criterion that combines 1 and 2 inwhich 1 is used as the basic criterion, and 2 is used solely to fill inthose cells that have been left with the background value and to fix anypossible discontinuities. This is the recommended option if theraster is newly created or if a background value has been defined.

Nevertheless, the central point criterion with background value('2' and background parameter) is recommended for filling continuitygaps that are left when generating files using the area criterion, but itmay also have other applications.

For line files, there are three criteria (1, 2 and 4):

For point files the raster cell for each point is simply that cell in which the point falls.

This application includes and augments the functions of the applications TiraLin and TiraPol that are no longer included in MiraMon version 4.

Dialog box of the application
TiraVec dialog box

Syntax

Syntax:

Parameters:

Modifiers: