# Types of Overlays and its funtions

**URL:** <https://community.thinkgeo.com/t/types-of-overlays-and-its-funtions/5913>\
**Category:** WebForms\
**Created:** [August 24, 2011, 1:51am UTC](https://community.thinkgeo.com/t/types-of-overlays-and-its-funtions/5913 "2011-08-24T01:51:48Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![KarunaKaran](https://community.thinkgeo.com/letter_avatar_proxy/v4/letter/k/977dab/32.png) [@KarunaKaran](https://community.thinkgeo.com/u/KarunaKaran)\
**Post date:** [August 24, 2011, 1:51am UTC](https://community.thinkgeo.com/t/types-of-overlays-and-its-funtions/5913/1 "2011-08-24T01:51:48Z")

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&nbsp;HI,

Can&nbsp;u&nbsp;please&nbsp;explain&nbsp;about&nbsp;the&nbsp;different&nbsp;types&nbsp;of&nbsp;Overlay&nbsp;and&nbsp;its&nbsp;function&nbsp;&nbsp;in&nbsp;Thinkgeo&nbsp;and&nbsp;especially&nbsp;about&nbsp;MinimumFeatureLayer.

&nbsp;

Regards

Karunakaran.M

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**Author:** ![Ethan](https://community.thinkgeo.com/user_avatar/community.thinkgeo.com/ethan/32/19964_2.png) [@Ethan](https://community.thinkgeo.com/u/Ethan)\
**Post date:** [August 25, 2011, 12:39pm UTC](https://community.thinkgeo.com/t/types-of-overlays-and-its-funtions/5913/2 "2011-08-25T12:39:16Z")

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Karunakaran,&nbsp;  
&nbsp;&nbsp;  
&nbsp;We&nbsp;have&nbsp;many&nbsp;types&nbsp;of&nbsp;overlay,&nbsp;at&nbsp;most&nbsp;time&nbsp;we&nbsp;used&nbsp;is&nbsp;LayerOverlay&nbsp;and&nbsp;some&nbsp;special&nbsp;overlay&nbsp;like&nbsp;GoogleOverlay.&nbsp;  
&nbsp;&nbsp;  
&nbsp;LayerOverlay&nbsp;need&nbsp;you&nbsp;provide&nbsp;data&nbsp;source&nbsp;local&nbsp;and&nbsp;some&nbsp;overlays&nbsp;like&nbsp;GoogleOverlay&nbsp;directly&nbsp;get&nbsp;image&nbsp;from&nbsp;online&nbsp;server.&nbsp;  
&nbsp;&nbsp;  
&nbsp;I&nbsp;am&nbsp;not&nbsp;sure&nbsp;which&nbsp;overlay&nbsp;you&nbsp;are&nbsp;interested&nbsp;in,&nbsp;but&nbsp;I&nbsp;think&nbsp;you&nbsp;can&nbsp;get&nbsp;detail&nbsp;information&nbsp;in&nbsp;our&nbsp;[wiki.thinkgeo.com](http://wiki.thinkgeo.com).&nbsp;  
&nbsp;&nbsp;  
&nbsp;For&nbsp;MinimumFeatureLayer&nbsp;I&nbsp;haven’t&nbsp;found&nbsp;it&nbsp;in&nbsp;our&nbsp;Core&nbsp;and&nbsp;WebEdition,&nbsp;please&nbsp;let&nbsp;us&nbsp;know&nbsp;where&nbsp;you&nbsp;get&nbsp;that?&nbsp;  
&nbsp;&nbsp;  
&nbsp;Regards,&nbsp;  
&nbsp;&nbsp;  
&nbsp;Don

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**Author:** ![KarunaKaran](https://community.thinkgeo.com/letter_avatar_proxy/v4/letter/k/977dab/32.png) [@KarunaKaran](https://community.thinkgeo.com/u/KarunaKaran)\
**Post date:** [August 26, 2011, 2:42am UTC](https://community.thinkgeo.com/t/types-of-overlays-and-its-funtions/5913/3 "2011-08-26T02:42:10Z")

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Don,&nbsp;  
&nbsp;&nbsp;  
&nbsp;In&nbsp;[wiki.thinkgeo.com](http://wiki.thinkgeo.com)&nbsp;i&nbsp;can&nbsp;get&nbsp;code&nbsp;samples&nbsp;at&nbsp;high&nbsp;level.&nbsp;Where&nbsp;can&nbsp;i&nbsp;get&nbsp;the&nbsp;code&nbsp;samples&nbsp;for&nbsp;the&nbsp;implementation&nbsp;of&nbsp;the&nbsp;various&nbsp;properties&nbsp;or&nbsp;methods&nbsp;of&nbsp;classes?&nbsp;I&nbsp;need&nbsp;to&nbsp;know&nbsp;how&nbsp;to&nbsp;implement&nbsp;the&nbsp;AddFeature&nbsp;method&nbsp;of&nbsp;Feature&nbsp;class&nbsp;using&nbsp;columnValues.&nbsp;Can&nbsp;you&nbsp;please&nbsp;help&nbsp;me?

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**Author:** ![KarunaKaran](https://community.thinkgeo.com/letter_avatar_proxy/v4/letter/k/977dab/32.png) [@KarunaKaran](https://community.thinkgeo.com/u/KarunaKaran)\
**Post date:** [August 26, 2011, 2:47am UTC](https://community.thinkgeo.com/t/types-of-overlays-and-its-funtions/5913/4 "2011-08-26T02:47:27Z")

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Sorry&nbsp;Don,&nbsp;i&nbsp;want&nbsp;to&nbsp;know&nbsp;about&nbsp;the&nbsp;implementation&nbsp;of&nbsp;the&nbsp;constructor&nbsp;of&nbsp;Feature&nbsp;class,&nbsp;AddFeature&nbsp;of&nbsp;InMemoryFeatureSource&nbsp;class.

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**Author:** ![Ethan](https://community.thinkgeo.com/user_avatar/community.thinkgeo.com/ethan/32/19964_2.png) [@Ethan](https://community.thinkgeo.com/u/Ethan)\
**Post date:** [August 26, 2011, 12:43pm UTC](https://community.thinkgeo.com/t/types-of-overlays-and-its-funtions/5913/5 "2011-08-26T12:43:02Z")

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Karunakaran,&nbsp;&nbsp;  
&nbsp;&nbsp;  
&nbsp;I&nbsp;think&nbsp;I&nbsp;haven’t&nbsp;totally&nbsp;understand&nbsp;your&nbsp;purpose.&nbsp;  
&nbsp;&nbsp;  
&nbsp;In&nbsp;constructor&nbsp;of&nbsp;Feature,&nbsp;we&nbsp;initializes&nbsp;columnValues,&nbsp;WKB&nbsp;and&nbsp;ID,&nbsp;if&nbsp;you&nbsp;pass&nbsp;in&nbsp;them&nbsp;via&nbsp;parameters,&nbsp;we&nbsp;will&nbsp;record&nbsp;that.&nbsp;  
&nbsp;&nbsp;  
&nbsp;The&nbsp;AddFeature&nbsp;function&nbsp;add&nbsp;feature&nbsp;to&nbsp;a&nbsp;internal&nbsp;Dictionary\<string,&nbsp;Feature\>.&nbsp;  
&nbsp;&nbsp;  
&nbsp;I&nbsp;don’t&nbsp;think&nbsp;these&nbsp;information&nbsp;helpful&nbsp;for&nbsp;you,&nbsp;but&nbsp;I&nbsp;am&nbsp;not&nbsp;sure&nbsp;what&nbsp;you&nbsp;want.&nbsp;  
&nbsp;&nbsp;  
&nbsp;Regards,&nbsp;  
&nbsp;&nbsp;  
&nbsp;Don

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<div class="post-metadata">

**Author:** ![KarunaKaran](https://community.thinkgeo.com/letter_avatar_proxy/v4/letter/k/977dab/32.png) [@KarunaKaran](https://community.thinkgeo.com/u/KarunaKaran)\
**Post date:** [August 29, 2011, 1:19am UTC](https://community.thinkgeo.com/t/types-of-overlays-and-its-funtions/5913/6 "2011-08-29T01:19:59Z")

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Don,&nbsp;  
&nbsp;&nbsp;  
&nbsp;Can&nbsp;you&nbsp;please&nbsp;get&nbsp;me&nbsp;a&nbsp;code&nbsp;sample&nbsp;for&nbsp;creating&nbsp;a&nbsp;feature&nbsp;with&nbsp;columnValues.&nbsp;I&nbsp;am&nbsp;not&nbsp;sure&nbsp;what&nbsp;the&nbsp;columnValues&nbsp;means.

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**Author:** ![Ethan](https://community.thinkgeo.com/user_avatar/community.thinkgeo.com/ethan/32/19964_2.png) [@Ethan](https://community.thinkgeo.com/u/Ethan)\
**Post date:** [August 29, 2011, 12:21pm UTC](https://community.thinkgeo.com/t/types-of-overlays-and-its-funtions/5913/7 "2011-08-29T12:21:10Z")

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Hi&nbsp;Karunakaran,&nbsp;  
&nbsp;&nbsp;  
&nbsp;Here&nbsp;is&nbsp;a&nbsp;very&nbsp;simple&nbsp;sample&nbsp;for&nbsp;ColumnValues.&nbsp;  
&nbsp;&nbsp;  
&nbsp;Feature&nbsp;feature1&nbsp;=&nbsp;new&nbsp;Feature(0,&nbsp;0);&nbsp;  
&nbsp;feature1.ColumnValues.Add("ColumnName",&nbsp;"10");&nbsp;  
&nbsp;&nbsp;  
&nbsp;The&nbsp;"ColumnValues"&nbsp;is&nbsp;a&nbsp;group&nbsp;of&nbsp;additional&nbsp;data&nbsp;which&nbsp;related&nbsp;with&nbsp;the&nbsp;contained&nbsp;shape&nbsp;of&nbsp;the&nbsp;feature.&nbsp;  
&nbsp;&nbsp;  
&nbsp;You&nbsp;know&nbsp;one&nbsp;feature&nbsp;contains&nbsp;a&nbsp;"BaseShape",&nbsp;it&nbsp;cannot&nbsp;record&nbsp;any&nbsp;other&nbsp;information&nbsp;exception&nbsp;the&nbsp;shape&nbsp;facility.&nbsp;If&nbsp;you&nbsp;have&nbsp;some&nbsp;POI&nbsp;points&nbsp;,&nbsp;the&nbsp;"BaseShape"&nbsp;only&nbsp;tell&nbsp;you&nbsp;where&nbsp;the&nbsp;point&nbsp;is,&nbsp;you&nbsp;cannot&nbsp;know&nbsp;what&nbsp;the&nbsp;point&nbsp;means&nbsp;for.&nbsp;Now&nbsp;you&nbsp;need&nbsp;add&nbsp;your&nbsp;information&nbsp;to&nbsp;"ColumnValues",&nbsp;like&nbsp;name,&nbsp;category,&nbsp;remarks&nbsp;etc.&nbsp;So&nbsp;when&nbsp;this&nbsp;feature&nbsp;render&nbsp;in&nbsp;map,&nbsp;the&nbsp;map&nbsp;control&nbsp;can&nbsp;label&nbsp;it&nbsp;via&nbsp;its&nbsp;"name"&nbsp;column&nbsp;value.&nbsp;  
&nbsp;&nbsp;  
&nbsp;If&nbsp;you&nbsp;still&nbsp;have&nbsp;question&nbsp;about&nbsp;this&nbsp;please&nbsp;let&nbsp;me&nbsp;know.&nbsp;  
&nbsp;&nbsp;  
&nbsp;Regards,&nbsp;  
&nbsp;&nbsp;  
&nbsp;Don