Image stacking takes the data from the bands of two rasters and combines them into a single multi-spectral image. Select the Image Stacking tool from the Advanced Tools menu to combine two images. You will also need to specify the folder location you would like the stacked image to be placed once the Image Stacking operation is complete.
Advanced tools
Image Stacking
DSM Height Extraction
NDVI
Change detection
Image Stacking
DSM Height Extraction
The DSM Height Extraction tool requires a source image with DSM (elevation) data. It allows you to select the source image and a vector layer with polygons overlapping it. The output is a new vector layer containing polygons with properties for minimum, maximum, and average (mean) elevation values calculated from the DSM data.
NDVI
Normalized Difference Vegetation Index (NDVI) quantifies vegetation by measuring the difference between near-infrared (which vegetation strongly reflects) and red light (which vegetation absorbs).
The expected input to the NDVI tool is an image that contains a red band and a near-infrared (NIR) band. Once you have selected the NDVI tool, you can select the index number of the bands for NIR and the visible Red band.
Change detection
The Format images for change detection tool allows you to combine two images – the “before” and “after” – into a single input image facilitating both change detection training and subsequent detection processes.
Image stacking takes the data from the bands of two rasters and combines them into a single multi-spectral image. Select the Image Stacking tool from the Advanced Tools menu to combine two images. You will also need to specify the folder location you would like the stacked image to be placed once the Image Stacking operation is complete.
For example, if you have Image A with 3 bands 1a,2a,3a and Image B with 3 bands 1b,2b,3b. Once the operation has been completed, this would result in a new image named stacked-image output to the folder you have selected for output. The stacked image would contain 6 bands 1a,2a,3a,1b,2b,3b.
Suppose the two images are of different resolutions. In that case, the output image resolution is the higher resolution out of the two images, and the lower resolution image is upscaled to the highest.
The DSM Height Extraction tool requires a source image with DSM (elevation) data. It allows you to select the source image and a vector layer with polygons overlapping it. The output is a new vector layer containing polygons with properties for minimum, maximum, and average (mean) elevation values calculated from the DSM data.
Normalized Difference Vegetation Index (NDVI) quantifies vegetation by measuring the difference between near-infrared (which vegetation strongly reflects) and red light (which vegetation absorbs).
The expected input to the NDVI tool is an image that contains a red band and a near-infrared (NIR) band. Once you have selected the NDVI tool, you can select the index number of the bands for NIR and the visible Red band.
The NDVI tool will output a new multi-spectral image named ndvi.
Note that band indices start at 1. So if your image has the following bands: RGB+NIR, the index of the red band is 1, and the index of the NIR band is 4.
The Format images for change detection tool allows you to combine two images – the “before” and “after” – into a single input image facilitating both change detection training and subsequent detection processes. It is similar to the image stacking tool but is performing additional checks to make sure the generated image is suitable for change detection.
