This module is designed to permit the extraction and parsing of the "GeoTIFF" Key entries from the TIFF image file.
| Name | Type | Description | UI Control |
| Filename | string | The filename of the input image. | FileDialog |
| InputMode | enum | The mode of Data input. | Menu |
| ChipStartRow | int | The starting position of clipping in row direction. | Field |
| ChipStartColumn | int | The starting position of clipping in row direction. | Field |
| ChipNumberOfRows | int | The number of rows for clipping. | Field |
| ChipNumberOfColumns | int | The number of columns for clipping. | Field |
| ChipSouthLatitude | int | The latitude of clipping in south. | Field |
| ChipNorthLatitude | int | The latitude of clipping in north. | Field |
| ChipWestLongitude | int | The longitude of clipping in west. | Field |
| ChipEastLongitude | int | The longitude of clipping in east. | Field |
| FileSouthLatitude | int | The longitude of image boundary in south (read only). | Field |
| FileWestLongitude | int | The longitude of image boundary in west (read only). | Field |
| FileNorthLatitude | int | The longitude of image boundary in north (read only). | Field |
| FileEastLongitude | int | The longitude of image boundary in east (read only). | Field |
| FileLongitudeResolution | int | The resolution of image file in longitude direction (read only). | Field |
| FileLatitudeResolution | int | The resolution of image file in latitude direction (read only). | Field |
| Name | Type | Description | |
| out | Mesh+Data | output field of 2D image. | |
| obj | DataObject | directly renderable object | |
ReadGeoTiff is used to extract the "GeoTIFF" key entry from a tiff image file and visualizes the geometrical information by rendering image with different colors to represent different height levels. The original tiff image is grey and output image is chromatic.
The macro includes a user interface. The clipping rectangle can be controlled from the user interface panel. The user interface also gives the information about the dimemsion and resolution of geometry.
ChipStartRow; ChipStartColumn; ChipNumberOfRows; ChipNumberOfColumns
The clipping rectangle defined by these four parameters.
ChipSouthLatitude; ChipNorthLatitude; ChipWestLongitude; ChipEastLongitude
Another way for defining the clipping rectangle.
FileSouthLatitude; FileWestLongitude; FileNorthLatitude; FileEastLongitude
The dimension of image boundary. it is read-only.
FileLongitudeResolution; FileLatitudeResolution
The resolution of geometrical information both in longitude and latitude direction. it is also read-only.
out
The output field of the ReadGeoTiff macro is a 2D field data of colour image.
obj
The output of the ReadGeoTiff macro as a directly renderable object which can be used with the UViewer.
The User Macro ReadGeoTiff makes use of the Functional Macro ReadGeoTiffFunc and the UI Macro ReadGeoTiffUI.
An example application ReadGeoTiff_Eg is provided, which uses the tiff image file, to display a 2D color image with geometrical information.
iac_proj/ReadGeoTiff/ReadGeoTiff_mods.v contains the V definitions of the ReadGeoTiffParams parameter block and the ReadGeoTiff module.
iac_proj/ReadGeoTiff/ReadGeoTiff_macs.v contains the V definitions of the ReadGeoTiffFunc Functional Macro, the ReadGeoTiffUI User Interface Macro, and the ReadGeoTiff User Macro.
iac_proj/ReadGeoTiff/ReadGeoTiff_apps.v contains the V definition of the example application ReadGeoTiff_Eg.
This module uses a open-source library (LIBTIFF) to read and write the tiff image files. The latest version of libtiff may be found at: ftp://ftp.sgi.com/graphics/tiff and is in compressed tar format. This module use the part of source code of this library to minimize the module size.
The library is embedded in the project and is compiled automatically when the project is compiled. Therefore it is necessary to have the complete path of the IAC-directory in the avsenv file. The standard avsenv file is not sufficient for this project as it only has a `.' as project directory.
Niles D. Ritter
MA YingLiang Manchester Visualization Centre
International AVS Centre Manchester Visualization Centre Manchester Computing University of Manchester Oxford Road Manchester United Kingdom M13 9PL