Using the parameters of the previous example the ground range resolution is 19 metersĬ. Computing the ground range resolution: see figure below which represents the range geometry vs the ground geometry The 3 requested parameters are the following:ī. sml extension.Įxample: the requested parameters are saved in a file called filename_slc.sml (with filename the name of the file which contains the SLC image). These parameters can be collected from the SLC image header file in SARscape which has a. * the azimuth resolution of the image: Δx
Range resolution calculator manual#
Manual computation: here are the steps to manually evaluate the number of looks to obtain an output image with a square pixel.Ī.
Range resolution calculator how to#
How to determine the number of looks to compute a square pixel:ġ. The appropriate number of looks can then be evaluated in order to obtain an output azimuth resolution similar to the range one (see below). Applying the multilooking only in the azimuth direction will only reduce the azimuth resolution. The higher the number of looks the lower the resolution. Square pixel computation: averaging the different looks of one single image will result in a loss of resolution. If the standard deviation decreases the SNR will increase.Ģ. The SNR corresponds to the ratio between the mean and the standard deviation of the data. Averaging different looks of one SLC image will keep the mean of the data and will decrease their standard deviation. Speckle reduction: one way to reduce the speckle on one SLC image is to increase its SNR (Signal to Noise ratio).
Why multilooking will reduce speckle and output a square pixel image:ġ. The resulting pixels on SLC radar images are then not squared and the SLC image will usually have more pixels in azimuth than in range for a same extent in range and azimuth. It will allow you to obtain a square pixel on the output image: the azimuth resolution of a SAR image is usually better than the range one. The speckle is directly related to the SAR system acquisition.Ģ. These interferences result in a grainy appearance of the image especially above homogeneous areas. It will reduce the speckle due to constructive and destructive interferences between the different backscattered signals from the different ground targets. There are two reasons of completing this process:ġ. This Help Article explains how a user can estimate the appropriate number of looks when multilooking RADAR images using SARscape.ĭuring the multilooking step of the SARscape basic module, an SLC (Singe Look Complex) radar image is divided in different looks characterized by different frequencies.
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