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

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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 Miniconference May 12,
2005 at UC Berkeley
http//seek.ecoinformatics.org http//www.kepler-p
roject.org
This material is based upon work supported by the
National Science Foundation under award 0225676.
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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

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GDAL - Geospatial Data Abstraction Library
http//www.remotesensing.org/gdal/
GDAL translator library connected to Kepler
actors via JNI GDAL can input 40 different
raster formats Conversion between different
projections possible File format
conversions also possible
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Java Actors for Handling ASC Grid Files

• 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/
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Java Routines for Convex Hull Calculation and
Rasterization

• 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 2
Scale Factor 1
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Java Actors for Rescaling and Merging

• Java actors can rescale ASCII grid files,
  changing resolution and extent
• Both nearest-neighbor and Inverse-Distance-Weighte
  d 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

Rescale and Clip
Merge
Start
Finish
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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

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

• Advantages
• Avoids including the whole GRASS distribution
  (100M) Light-weighted
• Allows defining common error coding between
  C/Java codes More robust

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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