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Raster Analysis in the Browser Brendan Collins, Blue Raster LLC

Raster Analysis in the Browser Brendan Collins, Blue Raster LLC. Rasters…. Elevation Slope Rainfall Temperature. Anatomy of the Web Map. client provides parameters. server returns results. Server-side Solution. The client provides parameters and. t he server returns results.

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Raster Analysis in the Browser Brendan Collins, Blue Raster LLC

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  1. Raster Analysis in the BrowserBrendan Collins, Blue Raster LLC

  2. Rasters… • Elevation • Slope • Rainfall • Temperature

  3. Anatomy of the Web Map client provides parameters. server returns results.

  4. Server-side Solution The client provides parameters and the server returns results.

  5. Client-side Solution The client does the analysis and the server provides source data.

  6. Client-side Raster Analysis Needs… • Source Data – (PNG / JPG) • PNG for rasters classified into discrete classes • JPEG for smooth continuous surfaces • Common screen size = 1024 x 768 = 786,432 • Suitability Analysis of 10 Layers = 8 Megapixels

  7. Transferring Source Data… • Continuous Data • JPEG with 60% compression • Note min/max of each dataset • Stretch dataset from black to white

  8. Transferring Source Data… • Discrete Data (Soil Type) • PNG8 or PNG24 • ***Symbolize data with known values***

  9. 32 Classes of ColorClass Hex ArcMap Client-side 1 0x7 7 0.03125 2 0xf 15 0.0625 3 0x17 23 0.09375 4 0x1f 31 0.125 5 0x27 39 0.15625 6 0x2f 47 0.1875 … 30 0xef 239 0.9375 31 0xf7 247 0.96875 32 0xff 255 1.0

  10. Start with grayscales… Start with Grayscales

  11. Red Channel = Green Channel = Blue Channel

  12. Red Channel = Elevation; Green Channel = Slope; Blue Channel = Drainage;

  13. Red = Soil Type; Green = Soil Acidity; Blue = Soil Depth;

  14. Merging Images Python

  15. Client-side Raster Analysis Needs… • Ability to run analysis • Access to individual pixels • Logic to evaluate pixel values • Raw speed

  16. Access to individual pixels • Flash – Pixel Bender or Bitmap API • Javascript – Ext JS 4 w/Pixel Bender • Silverlight – Pixel Shader • I recommend Flash/Flex with Pixel Bender

  17. Pixel Bender Kernel Language • Override a single function (evaluatePixel) • Executes in CPU / GPU • Simple Syntax but Limited Expressiveness • No Arrays • No Custom Functions • boolean, float, pixel, and image data types

  18. Map Algebra Expression

  19. Be kind to your Kernel

  20. Thank Youbcollins@blueraster.com

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