# Presentation: 668487

## Introduction to MISR Data Analysis and Tools

**Brian E. Rheingans**
**Jet Propulsion Laboratory, **
**California Institute of Technology**
**Workshop on Exploring and Using MISR Data**
**EGS-AGU-EUG Joint Assembly**
**Nice, France**
**April 2003**

## SOM Background

**The Space Oblique Mercator **
**(SOM) map projection was**
**developed to support LandSat**
**which covers the same**
**large geographic extent as**
**MISR.**
**SOM was designed to minimize**
**the shape distortion and scale**
**errors throughout the length **
**of the MISR swath near the**
**satellite ground track.**
**SOM X is in the direction of the**
**Spacecraft ground track and**
**SOM Y is perpendicular X**

## SOM Background

** ****Terra follows a pattern of orbits which repeats after 233 unique orbits**
** ****Each of the 233 possible orbits is called a path**
** ****SOM defines a separate projection for each of these paths**
** ****For MISR, a path begins at a particular longitude as the satellite**
**  ****crosses the ascending node.**
** ****This path implies a specific longitude of ascending node, which implies**
**   ****a specific SOM projection applicable to that path**

## MISR Orbital Paths/Blocks

## MISR HDF-EOS “Stacked Block” File vs. Aligned Image

- Red Channel Grid SDS (180 Stacked Blocks)

- SOM coordinates of top-block corners part of
- Grid metadata.
- -Projection and orbital parameters part of Grid
- Metadata
- Offsets of each block from the one above is part
- of Stacked-block grid extension metadata.

- Block
- dimension

-  Sample dim / SOM Y

- Line dim / SOM X

- Stacked blocks are due to
- the large geographic extent
- Of the MISR swath

## HDF-EOS Background

**HDF-EOS routines do NOT assemble the**
**Blocks.  That is left for the user.**
**180 blocks are defined for every MISR**
**Product to make block index in absolute.**
**However, roughly 142 blocks have data for**
**Any given orbit.  The extra blocks are to**
**Allow for seasonal variation.**
**We are working on a summary product**
**Specification that will not use the dreaded**
**Stacked blocks, although we will preserve**
**Them for Standard Processing.**

## Where does this pixel belong?

- Inside the HDF-EOS “stacked block grid” = (block, line, sample)
- Convert (block, line, sample) <-> SOM
- Requires several metadata values and some arithmetic.
- Convert SOM <-> Lat/Lon
- Requires use of GCTP map projection coordinate conversion library in HDF-EOS distribution.
- This process is described in the _MISR Data Product Specification_, Appendix A.
- Or simply look up corresponding block, line, sample in the AGP dataset.

## L1B2 Browse Products

**JPEG format true-color imagery, all 9 cameras, 2.2 km sampling**

**Color, multi-angle browse products **
**and on-line interactive viewer **
**http://eosweb.larc.nasa.gov/MISRBR/**

**Actual browse resolution**

**Actual browse extent**

## Data visualization and analysis tools

**·misr_view (IDL-based)**
**·hdfscan (Tcl/tk and Fortran90 based)**
**· HDF-to-binary converter**
**·HDF-EOS to GeoTIFF converter (HEG)**
**http://eosweb.larc.nasa.gov/PRODOCS/misr/misr_tools.html**

## Hdfscan

- • Very useful during the debugging process
- • Displays all HDF-EOS Attributes, SDS’s, Vdata’s easily
- • Allows minor editing of the HDF-EOS file
- • Performs some statistics on the data.
- • Does not assemble MISR blocks
- • Only available on SGI Irix and Sun Solaris

## Hdfscan - Locate Path/Block Display using AGP

## ERDAS Imagine 8.5

- • We wrote custom import routines to convert MISR HDF-EOS files into Imagine
- files preserving geolocation via projection parameters to facilitate geo-calibration.
- • Unfornuately, these are not generally available and are only for SGI Irix.
- • An alternative may be using - **HDF-EOS to GeoTIFF converter (HEG)**
- http://support.erdas.com/downloads/hdf-eos/hef-eos_to_geotiff.asp

## ERDAS Imagine – Full Swath/Full Res. Geo-linked

## ERDAS Imagine – Raster/Vector Overlay

## ERDAS Imagine – GIS Data Analysis

## MISRView

- • Maps path/orbit to time and date
- • Assembles MISR blocks
- • Reports geolocation using the AGP
- • Displays true color MISR imagery
- • Can reproject MISR imagery
- • Requires IDL

- • Perspective tool
- • Band slider tool
- • Scroll tool
- • Vector overlay tool
- • Reprojection tool
- • Color / Contrast tools

## MISRView – Main Menu

## MISRView – L1B2 imagery

## MISRView – MISR Vision (R-Ba, G-An, B-Bf)