Before and after: Radiometrically terrain-corrected ALOS PALSAR image of part of the Alaska Range in Denali National Park before (left) and after (right) power-scale conversion in ArcGIS. Credit: ASF DAAC 2016; Includes Material © JAXA/METI 2006.

How to View Radiometrically Terrain-Corrected (RTC) Images in ArcGIS

Before and after: Radiometrically terrain-corrected ALOS PALSAR image of part of the Alaska Range in Denali National Park before (left) and after (right) power-scale conversion in ArcGIS. Credit: ASF DAAC 2016; Includes Material © JAXA/METI 2006.

Source: Rick Guritz, ASF

Easier (Windows): Convert power (dark) to db (light)

In this document you will find:

Background

Prerequisites

Steps

Example Images

Background

The standard output of the RTC process is a gamma0 power image. This format supports statistical assessments of the data. However, when displayed in GIS software, data in power format is dark. There are two common ways to deal with this in a GIS environment: convert the power scale to amplitude or convert it to decibels (dB). A comparison is available in the Example Images section, but dB converted images are generally preferred for visualization.

Prerequisites

Materials List:

    1. Windows PC
    2. RTC Image Source Options:

Steps

Open ArcMap in ArcGIS

Load an RTC image (.tif file) into ArcGIS

    1. Drag and drop the file into the Table of Contents window, or in the top menu click File > Add Data > Add Data
    2. Then click on the Connect to Folder button and navigate to the folder that contains the RTC image

Note: Ensure that the Spatial Analyst toolbox is checked in the Extensions section of the Customize tab.

Open the Raster Calculator (use search function to find calculator)

    1. Calculate the following conversions
      • Amplitude: SquareRoot(“RTC filename”)
      • Decibel (dB): dB = 10. * Log10(“RTC filename”)
    2. Set the Output Raster field to a directory of your choice and select OK
Raster Calculator set-up for amplitude conversion
Raster Calculator set-up for dB conversion

Example Images

A portion of the Alaska Range in Denali National Park in (A) RTC Gamma0 Image, (B) Amplitude Image, (C) dB Power Image. Credit: ASF DAAC 2016; Includes Material ©JAXA/METI 2006.

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