GIS Actors in Kepler - Java-based,

GDAL-JNI, and C++(Grass) Routines GIS Actors in Kepler - Java-based,

GDAL-JNI, and C++(Grass) Routines

Dan Higgins - UC Santa Barbara (NCEAS)Chad Berkley – UC Santa Barbara (NCEAS)

Jianting Zhang - University of New Mexico(LTER)

Prepared for the 6th Biennial Ptolemy MiniconferenceMay 12, 2005 at UC Berkeley

http://seek.ecoinformatics.orghttp://www.kepler-project.org

This material is based upon work supported by the National Science Foundation under award 0225676.

Goal : Predict Species Locations Based on Known Locations and Climate/Geographic

Spatial Data

• Goal is to correlate spatial data with known locations to predict other locations where a species might exist (Environmental Niche Modeling)

• Requires manipulation of geographically referenced point data and GIS raster data from variety of sources

GDAL - Geospatial Data Abstraction Libraryhttp://www.remotesensing.org/gdal/

GDAL translatorlibrary connected toKepler actors via JNI

GDAL can input ~40different raster formats

Conversion betweendifferent projectionspossible

File format conversionsalso possible

Java-based actors created to read and manipulate ASCII grid files

ImageJ image processing package from NIH added as an actor to display and manipulate images

ImageJ has macro capabilities & numerous plug-ins

ImageJ - http://rsb.info.nih.gov/ij/

Java Actors for Handling ASC Grid Files

Convex Hull algorithm relatively easy to implement in Java

Java routines for the Convex Hull convert the polygon to a shape which can be ‘scaled’ in size

Scale Factor = 1Scale Factor = 2

Java Routines for Convex Hull Calculation and Rasterization

Java Actors for Rescaling and Merging

Java actors can rescale ASCII grid files, changing resolution and extent

Both nearest-neighbor and Inverse-Distance-Weighted algorithms implemented

Disk-based code allows very large grids to be manipulated (i.e not limited by RAM)

Grid rasters can be ‘merged’ with various operations on data in overlapping pixels

Start

Rescale and Clip

Merge

Finish

GRASS - Geographic Resources Analysis Support System (http://grass.itc.it/)

Functionality• Polygon

Rasterization• Raster

Buffering

Method• Extracting C

source codes of the modules and related routines

• Using JNI to interface with Kepler/Ptolemy

Advantages

•Avoids including the whole GRASS distribution (~100M) – Light-weighted

•Allows defining common error coding between C/Java codes – More robust

GRASS –Cont.Based on Version 5.7 (Most Recent 6.0)

SUMMARY

Several methods have been used to create actors which implement GIS operations

Types of operations limited to those needed for specific species distribution workflow

Emphasis has been on raster operations; some vector operations will be implemented in future

Other efforts are implementing GIS operations using Web Services