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

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Presentation on theme: "Raster Analysis in the Browser Brendan Collins, Blue Raster LLC."— Presentation transcript:

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 0x xf x x1f x x2f … 30 0xef xf xff

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


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