I have a geotiff image feeding a rasterToPolygonCoercer. I need to assign the value of the output polygons based on the input raster palette and value. How do I feed the MapInfo TAB writer the correct color from the RasterToPolygoneCoercer?
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RasterToPolygonCoercer assign color to output polygons
Best answer by takashi
H @jayrussell, if the raster has a palette to define colors, at first you will have to resolve the palette to transform the raster from the single band (palette entry) to 3 bands (color elements: R, G, B). You can use the RasterPaletteResolover here.
The RasterToPolygonCoercer adds an attribute called "_label" to the output polygons, which stores comma separated cell values. In the case where the raster interpretation was RGB24 (3 bands = Red8, Green8, Blue8), each cell value is in the range 0-255.
FME requires comma separated color values normalized in the range 0-1 for setting a color to features, so you also will have to add a process to normalize the color value.
This is an example, assuming that the palette defines RGB24 color.
Hope this helps.
Hi @jayrussell
I think my answer to this post: https://knowledge.safe.com/questions/78473/convert-raster-to-vector-grid-populate-attributes.html?childToView=78480#answer-78480 is what you are after.
- Best Answer
H @jayrussell, if the raster has a palette to define colors, at first you will have to resolve the palette to transform the raster from the single band (palette entry) to 3 bands (color elements: R, G, B). You can use the RasterPaletteResolover here.
The RasterToPolygonCoercer adds an attribute called "_label" to the output polygons, which stores comma separated cell values. In the case where the raster interpretation was RGB24 (3 bands = Red8, Green8, Blue8), each cell value is in the range 0-255.
FME requires comma separated color values normalized in the range 0-1 for setting a color to features, so you also will have to add a process to normalize the color value.
This is an example, assuming that the palette defines RGB24 color.
Hope this helps.
takashi wrote:
H @jayrussell, if the raster has a palette to define colors, at first you will have to resolve the palette to transform the raster from the single band (palette entry) to 3 bands (color elements: R, G, B). You can use the RasterPaletteResolover here.
The RasterToPolygonCoercer adds an attribute called "_label" to the output polygons, which stores comma separated cell values. In the case where the raster interpretation was RGB24 (3 bands = Red8, Green8, Blue8), each cell value is in the range 0-255.
FME requires comma separated color values normalized in the range 0-1 for setting a color to features, so you also will have to add a process to normalize the color value.
This is an example, assuming that the palette defines RGB24 color.
Hope this helps.
Is there a way to retain the original palette index that was present before the RasterPaletteResolver? It represents a radar reflectivity dB that I need to retain along with assigning a color.
takashi wrote:
H @jayrussell, if the raster has a palette to define colors, at first you will have to resolve the palette to transform the raster from the single band (palette entry) to 3 bands (color elements: R, G, B). You can use the RasterPaletteResolover here.
The RasterToPolygonCoercer adds an attribute called "_label" to the output polygons, which stores comma separated cell values. In the case where the raster interpretation was RGB24 (3 bands = Red8, Green8, Blue8), each cell value is in the range 0-255.
FME requires comma separated color values normalized in the range 0-1 for setting a color to features, so you also will have to add a process to normalize the color value.
This is an example, assuming that the palette defines RGB24 color.
Hope this helps.
takashi wrote:
Do you mean that both the palette index and the color value (R, G, B) should be extracted? Or, need to extract only the palette index?
takashi wrote:
Do you mean that both the palette index and the color value (R, G, B) should be extracted? Or, need to extract only the palette index?
takashi wrote:
Do you mean that both the palette index and the color value (R, G, B) should be extracted? Or, need to extract only the palette index?
takashi wrote:
Do you mean that both the palette index and the color value (R, G, B) should be extracted? Or, need to extract only the palette index?
The order of bands (palette index -> color, or color -> palette index) can be controlled by setting the Connection Runtime Order at the output port (right-click > Set Connection Runtime order) where the data flow branches into two streams. e.g. at the Junction in the screenshot below.
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