ian.anderson
Download model and SAF file
Description:
This model was designed to produce a layer-stacked composite image to be used for segmentation purposes, the particular variables involved having been determined to be optimal for producing segments appropriate to vegetation mapping. Increased segmentation accuracy in turn bolsters the accuracy of any subsequent OBIA. The model calculates NDVI from NAIP imagery (assuming Red is band 1 and NIR is band 4), Trishade (aka fully illuminated hillshade) from a DEM, the first Principal Component (reflectivity of surfaces from all band inputs) from a Landsat image, and stacks these calculated layers with the original 4 bands of the NAIP image. A Spectral Attribute File (.saf) is also provided to make it easier to select predefined band combinations for displaying the stacked data. Drop the .saf into your $IMAGINE_HOME\etc directory (and restart ERDAS IMAGINE) to access these band combinations.
Note that all input imagery has been resampled to a common pixel size (usually 10m). Slight modifications may be required if the inputs vary in pixel size, such as selecting more appropriate resampling techniques.Note that the original design makes several assumptions:
- That NoData has not been set on the input imagery - if your data does have NoData defined (for example, you are using DTED elevation data) then you may wish to remove the Set To NoData operators in the appropriate sub-models.
- That the NAIP imagery is 8-bit (and therefore the output data type is 8-bit).
- Also remember that NAIP imagery is organized in wavelength order of RGBN, as opposed to the more prevalent satellite imagery order of BGRN. If you are using data other than NAIP you will need to adjust the bands used in the NDVI sub-model. The SAF also assumes a RGBN band order.
| ForestryLayerstack-v15-1-0.gmdx |
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| Stretched NDVI submodel |
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| Modified Principal Components submodel |
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| Trishade submodel |
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Input parameters:
NAIP Filename In: NAIP input image; assumes band order is RGBN.
Landsat Filename In: Landsat input image for producing modified principal components.
Stats Skip Factor: Larger numbers will increase processing speed at the expense of some accuracy. 1 uses all pixels values, 4 uses every fourth row and column value, etc.
DEM Filename In: DEM input for producing trishade layers.
Layerstack Filename Out: Name of layerstack output image.
Output example:
| Shown below is the trishade portion of the 9-band output image, RGB set to bands 6,7,9: |
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