1. Raster Analysis in the Browser Brendan Collins, Blue Raster LLC

2. Rasters… Elevation Slope Rainfall Temperature

3. Anatomy of the Web Map Client Application (Firefox / IE/ Chrome) Spatial Data / Queries Mapping Server (ArcGIS Server) Application Server (IIS / Apache) Flash / JS / HTML client provides parameters. server returns results.

4. Server-side Solution Client Application (Firefox / IE/ Chrome) Server does the work Mapping Server (ArcGIS Server) Application Server (IIS / Apache) The client provides parameters and the server returns results.

5. Client-side Solution Client Application (Firefox / IE / Chrome) User’s Computer Does the Work Mapping Server (ArcGIS Server) Application Server (IIS / Apache) 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 Color Class 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 You bcollins@blueraster.com