Parent Topic: Supported File Formats

PAMAP

A PAMAP database typically consists of four files which must be kept together in same directory in order to be accessed. The .HDR file contains georeferencing information, PCTs, and LUTs. The .RFL file contains the raster data. The .VFL file contains vector data. The .DFL file contains attribute data.

PAMAP files are supported for import, and export, but not for live linking.

The GeoGateway model prohibits the creation of new PCTs and LUTs even though the PAMAP file format could support it. The model also prohibits the creation of multiresolution raster layers within a single database even though the PAMAP format could support it.

The following subtopics describe the limitations for each data type in more detail.

See Also: FIMPORT, FEXPORT

Raster Data
A PAMAP database can have zero or more raster (image) layers. In a PAMAP database, each layer covers the same area on the earth but each layer may be a different resolution. In order to comply with the GeoGateway data model, the width of the database is reported as the width of the highest resolution layer. The height of the database is reported as the height of the highest resolution layer. When reading multiresolution databases, applications should access all layers as if they were of the highest resolution. GeoGateway automatically replicates the pixel data for lower resolution layers.

PAMAP raster layers have either 1, 2, or 4 bytes per pixel. The mapping to GeoGateway is as follows: 

       PAMAP Size ->   GeoGateway ->   PAMAP Size
       1               8U              1
       -               16S             2
       2               16U             2
       4               32R             4
Currently, PAMAP raster layers can only be written once. When a PAMAP database is created or a raster layer is added, the layer can be written and rewritten in any order. Once the file is closed though, existing layers can only be read.

PAMAP databases further distinguish a raster layer as being either a "Polygon Cover", "Reference Cover", or "Surface Cover", GeoGateway can read all cover types. Only surface covers can be created and written to. The GeoGateway model prohibits the creation of new raster layers other than at the highest resolution currently in the database.

Georeferencing
PAMAP databases support all common datums and projections supported by PCIDSK files. All raster and vector layers have the same georeferencing in a PAMAP database.

PseudoColour Tables (PCT)
PCTs are referred to as Colour Look-up Tables (CLUTs) using the PAMAP terminology. CLUTs can have 1 to 256 entries and can be one of three types: RGB100 where the red, green, and blue intensities are in the range 0 to 100; RGB256 where the intensities are in the range 0 to 255; and HLS100 where the hue, lightness and saturation intensities are in the range 0 to 100.

Currently, only CLUTs of the RGB256 type with 256 entries are supported. The results of reading/writing other types is undefined.

Existing CLUTs can be read/written. The GeoGateway model prohibits the creation of new CLUTs.

Lookup Tables (LUT)
LUTs are referred to as Threshold Look-up Tables (TLUTs) using the PAMAP terminology. TLUTs can have 1 to 256 entries and have floating point values dividing each class or theme.

Currently, the only supported TLUTs are those with 256 entries and thresholds running sequentially from 0 to 255 and class/theme values in the range 0 to 255. The results of reading/writing other types is undefined.

Existing TLUTs can be read/written. The GeoGateway model prohibits the creation of new TLUTs.

Vectors (VEC)
PAMAP databases support points, polylines, and whole polygons. Currently, there is no support for topological polygons.

Each shape has a number of system defined attributes as well user defined attributes. Attributes can be floats, doubles, integers or strings.

New layers can be created in a PAMAP database through GeoGateway. The following keywords in the options string controls the type of layer created: 

Point - creates a point layer
Vector - creates a polyline layer
Polygon - creates a polygon layer
The keyword "LEVELxx" crates the layer on a specific level. For example, "Point LEVEL23" would create a point layer on level 23 of the PAMAP database. In the absence of keywords in the options string, the default behaviour is to create a polygon layer on the next available level.

Parent Topic: Supported File Formats
About PCI Help Gateway