# Raster overlay similar to heatmap

**URL:** <https://community.thinkgeo.com/t/raster-overlay-similar-to-heatmap/1283>\
**Category:** WinForms\
**Created:** [June 8, 2010, 8:20am UTC](https://community.thinkgeo.com/t/raster-overlay-similar-to-heatmap/1283 "2010-06-08T08:20:25Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Gregory](https://community.thinkgeo.com/letter_avatar_proxy/v4/letter/g/e56c9b/32.png) [@Gregory](https://community.thinkgeo.com/u/Gregory)\
**Post date:** [June 8, 2010, 8:20am UTC](https://community.thinkgeo.com/t/raster-overlay-similar-to-heatmap/1283/1 "2010-06-08T08:20:25Z")

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I&nbsp;would&nbsp;like&nbsp;to&nbsp;create&nbsp;a&nbsp;raster&nbsp;overlay&nbsp;similar&nbsp;to&nbsp;heatmap;&nbsp;however,&nbsp;my&nbsp;raster&nbsp;overlay&nbsp;marks&nbsp;up&nbsp;some&nbsp;features&nbsp;of&nbsp;the&nbsp;base&nbsp;image&nbsp;(for&nbsp;example,&nbsp;by&nbsp;highlighting&nbsp;the&nbsp;contour&nbsp;of&nbsp;the&nbsp;base&nbsp;image&nbsp;with&nbsp;another&nbsp;color).&nbsp;So&nbsp;my&nbsp;raster&nbsp;layer&nbsp;is&nbsp;a&nbsp;bitmap&nbsp;that&nbsp;must&nbsp;overlay&nbsp;the&nbsp;base&nbsp;image&nbsp;pixel&nbsp;for&nbsp;pixel&nbsp;(e.g.&nbsp;when&nbsp;the&nbsp;map&nbsp;is&nbsp;zoomed&nbsp;or&nbsp;panned,&nbsp;my&nbsp;raster&nbsp;overlay&nbsp;must&nbsp;zoom&nbsp;or&nbsp;pan&nbsp;in&nbsp;tandem&nbsp;with&nbsp;the&nbsp;map).&nbsp;What&nbsp;is&nbsp;the&nbsp;best&nbsp;approach?

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**Author:** ![ThinkGeo](https://community.thinkgeo.com/user_avatar/community.thinkgeo.com/thinkgeo/32/25029_2.png) [@ThinkGeo](https://community.thinkgeo.com/u/ThinkGeo)\
**Post date:** [June 9, 2010, 2:44am UTC](https://community.thinkgeo.com/t/raster-overlay-similar-to-heatmap/1283/2 "2010-06-09T02:44:52Z")

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Gregory,

Thanks&nbsp;for&nbsp;your&nbsp;posts.  
&nbsp;  
I&nbsp;am&nbsp;exactly&nbsp;sure&nbsp;about&nbsp;your&nbsp;requirement.&nbsp;Basically&nbsp;we&nbsp;can&nbsp;try&nbsp;to&nbsp;create&nbsp;our&nbsp;own&nbsp;RasterSource&nbsp;and&nbsp;RasterLayer&nbsp;probably&nbsp;from&nbsp;GdiPlusRasterSource&nbsp;or&nbsp;some&nbsp;other&nbsp;concrete&nbsp;raster&nbsp;source.  
  
&nbsp;  
`class MyRasterSource : GdiPlusRasterSource    {        protected override GeoImage GetImageCore(RectangleShape worldExtent, int canvasWidth, int canvasHeight)        {            //Get the background image first.            //Call the base.            // Draw them into one and return back.               }    }`  
  
Probablly&nbsp;I&nbsp;am&nbsp;misunderstanding&nbsp;something.It&nbsp;would&nbsp;be&nbsp;great&nbsp;if&nbsp;we&nbsp;can&nbsp;get&nbsp;into&nbsp;some&nbsp;concrete&nbsp;example.  
&nbsp;  
Any&nbsp;more&nbsp;questions&nbsp;just&nbsp;feel&nbsp;free&nbsp;to&nbsp;let&nbsp;me&nbsp;know.  
&nbsp;  
Thanks.  
&nbsp;  
Yale

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**Author:** ![Gregory](https://community.thinkgeo.com/letter_avatar_proxy/v4/letter/g/e56c9b/32.png) [@Gregory](https://community.thinkgeo.com/u/Gregory)\
**Post date:** [June 9, 2010, 6:06am UTC](https://community.thinkgeo.com/t/raster-overlay-similar-to-heatmap/1283/3 "2010-06-09T06:06:41Z")

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Hey,&nbsp;Yale!&nbsp;How&nbsp;do&nbsp;I&nbsp;make&nbsp;sure&nbsp;the&nbsp;raster&nbsp;image&nbsp;scales&nbsp;identically&nbsp;to&nbsp;the&nbsp;base&nbsp;image,&nbsp;which&nbsp;is&nbsp;a&nbsp;RasterImageLayer?&nbsp;When&nbsp;the&nbsp;map&nbsp;is&nbsp;panned,&nbsp;the&nbsp;RasterImageLayer&nbsp;automatically&nbsp;pans,&nbsp;so&nbsp;how&nbsp;do&nbsp;I&nbsp;make&nbsp;sure&nbsp;my&nbsp;image&nbsp;pans&nbsp;to&nbsp;the&nbsp;same&nbsp;degree?&nbsp;Do&nbsp;i&nbsp;need&nbsp;to&nbsp;associate&nbsp;my&nbsp;image&nbsp;with&nbsp;the&nbsp;same&nbsp;world&nbsp;file?

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**Author:** ![ThinkGeo](https://community.thinkgeo.com/user_avatar/community.thinkgeo.com/thinkgeo/32/25029_2.png) [@ThinkGeo](https://community.thinkgeo.com/u/ThinkGeo)\
**Post date:** [June 10, 2010, 3:32am UTC](https://community.thinkgeo.com/t/raster-overlay-similar-to-heatmap/1283/4 "2010-06-10T03:32:02Z")

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Gregory,&nbsp;  
&nbsp;&nbsp;  
&nbsp;Thanks&nbsp;for&nbsp;your&nbsp;response.&nbsp;  
&nbsp;&nbsp;  
&nbsp;As&nbsp;you&nbsp;already&nbsp;thought,&nbsp;the&nbsp;raster&nbsp;image&nbsp;should&nbsp;associate&nbsp;with&nbsp;some&nbsp;world&nbsp;file.&nbsp;&nbsp;This&nbsp;is&nbsp;the&nbsp;same&nbsp;logic&nbsp;when&nbsp;you&nbsp;load&nbsp;some&nbsp;raster&nbsp;image&nbsp;like&nbsp;ecw&nbsp;,&nbsp;tif&nbsp;etc,&nbsp;we&nbsp;must&nbsp;know&nbsp;its&nbsp;location&nbsp;by&nbsp;analyzing&nbsp;its&nbsp;world&nbsp;file.&nbsp;So&nbsp;probably&nbsp;you&nbsp;may&nbsp;need&nbsp;to&nbsp;do&nbsp;in&nbsp;the&nbsp;same&nbsp;way.&nbsp;  
&nbsp;&nbsp;  
&nbsp;Any&nbsp;more&nbsp;questions&nbsp;just&nbsp;feel&nbsp;free&nbsp;to&nbsp;let&nbsp;me&nbsp;know.&nbsp;  
&nbsp;&nbsp;  
&nbsp;Thanks.&nbsp;  
&nbsp;&nbsp;  
&nbsp;Yale&nbsp;