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supported_map_formats [2013/03/04 17:40] admin [GDAL Limitations] |
supported_map_formats [2013/08/21 23:06] admin |
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===== GDAL Limitations ===== | ===== GDAL Limitations ===== | ||
- | The GDAL implementation (and some times the underlying file format) imposes limitations on the representation of projections, layer names, category names and their corresponding colors. Some of these limitations and their corresponding workarounds are listed in the table below: | + | The GDAL implementation (and some times the underlying file format) imposes limitations to the representation of projections, layer names, category names and their corresponding colors. Some of these limitations and their corresponding workarounds are listed in the table below: |
^ Limitation ^ Workaround ^ | ^ Limitation ^ Workaround ^ | ||
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| Several file formats do not support storing category colors. | Use a [[supported_map_formats#Virtual Format|VRT file]] or an auxiliary PAM XML file to keep this information. The ERMapper file format has the best support to category names and colors. | | | Several file formats do not support storing category colors. | Use a [[supported_map_formats#Virtual Format|VRT file]] or an auxiliary PAM XML file to keep this information. The ERMapper file format has the best support to category names and colors. | | ||
| Several file formats do not support the storage of layer names. | Use a [[supported_map_formats#Virtual Format|VRT file]] or an auxiliary PAM XML file to keep this information. The ERMapper file format also has support to layer names. | | | Several file formats do not support the storage of layer names. | Use a [[supported_map_formats#Virtual Format|VRT file]] or an auxiliary PAM XML file to keep this information. The ERMapper file format also has support to layer names. | | ||
- | | The categories must start from 0 and their definition must be contiguous. | Unfortunately, the only way to workaround this limitation is defining dummy categories (Dinamica EGO does this when representing non-contiguous categories in a GDAL supported format) or using the ERMapper file format. | | + | | @yellow:The categories must start from 0 and their definition must be contiguous. | Unfortunately, the only way to workaround this limitation is defining dummy categories (Dinamica EGO does this when representing non-contiguous categories in a GDAL supported format) or using the ERMapper file format. | |
- | | Some formats using specified number of bits per sample, do not preserve category colors. | Unfortunately, the only way to workaround this limitation is using a different format or choosing a number of bits per sample that does not have this limitation for a given format. For example, Geotiff format only present category colors when 8 bits per pixel is used. | | + | | @yellow:Some formats do not preserve category colors when a specified number of bits per sample is used. | Unfortunately, the only way to workaround this limitation is using a different format or choosing a number of bits per sample that does not have this limitation for a given format. For example, Geotiff format only stores category colors when the cell type is 8 bits. | |
+ | | @pink:Categories represented by negative values are not supported. | Unfortunately, there is no way to workaround this limitation, except by avoiding the use of negative categories. | | ||
The ERMapper file format is handled by Dinamica EGO itself and not delegated to the GDAL library. For that reason, the PAM XML file can not be used with this format. | The ERMapper file format is handled by Dinamica EGO itself and not delegated to the GDAL library. For that reason, the PAM XML file can not be used with this format. | ||
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===== Dinamica EGO Limitations ===== | ===== Dinamica EGO Limitations ===== | ||