topic How to display 1 million points in the Map? in ArcGIS API for Silverlight Questions

How to display 1 million points in the Map?

SripathiRao — Thu, 21 Apr 2011 16:43:44 GMT

Hi,

I am new to arcGIS. I have requirement to display 1 million points in the Map. Can anyone guide me the efficient way to achieve this?

I have tried by using Graphic Layer by adding Graphic object to GraphicCollection, but it is taking indefinite time to display the points.

Any help will be highly appreciated.

Thanks in Anticipation,
Sripathi Rao

Re: How to display 1 million points in the Map?

JenniferNery — Thu, 21 Apr 2011 18:46:03 GMT

Kindly see post#2 in this thread: http://forums.arcgis.com/threads/27977-Cluster-of-50-000-Points-dynamically-add-remove-cluster

You can also look at this help doc: http://help.arcgis.com/en/webapi/silverlight/apiref/ESRI.ArcGIS.Client~ESRI.ArcGIS.Client.Layer.html

Re: How to display 1 million points in the Map?

wangzhifang — Thu, 21 Apr 2011 23:37:29 GMT

Here's a Chinese blog talk about how to achieve this in several situations, FYI.
http://blog.newnaw.com/?p=633

Re: How to display 1 million points in the Map?

SripathiRao — Mon, 25 Apr 2011 09:19:12 GMT

Thanks for the reply.

My requirement needs to display all the million points in the map without using the layers (featurelayer) for clusters. 1 million points must be visible in 40 sq. kms area.

The solution which I got above are using layers to display points as clusters.

Did arcGIS supports this kind of requirement?

Any workaround will be highly appreciated.

Thanks in Anticipation,
Sripathi Rao

Re: How to display 1 million points in the Map?

YamunadeviRathinasamy — Tue, 26 Apr 2011 19:43:49 GMT

I am doing this by the following steps:

1) Stored procedure to get 1million record based on the spatial filter. and it returns "OBJECTID.Convert(varchar(mx),GEOMETRY)"
2) Write WCF to call this procedure and get back the result using Datareader into List<string>
3) Write a parser to parse the geometry string into ESRI.arcGIS.Client.Geometry type
4) Create Graphic with symbol and the parsed geometry
5) Add to the graphics layer.

Re: How to display 1 million points in the Map?

IgressT — Wed, 27 Apr 2011 00:41:09 GMT

I am doing this by the following steps:

1) Stored procedure to get 1million record based on the spatial filter. and it returns "OBJECTID.Convert(varchar(mx),GEOMETRY)"
2) Write WCF to call this procedure and get back the result using Datareader into List<string>
3) Write a parser to parse the geometry string into ESRI.arcGIS.Client.Geometry type
4) Create Graphic with symbol and the parsed geometry
5) Add to the graphics layer.

Can you be more specific because I am dealing with just 20,000 points.
Because 1 million points is lot of data that is being returned
are you doing some kind of paging? If yes how are doing it (I mean how are you dealing with paging and adding to the data to the map)
Adding all points to graphics layer will freeze up browser are you doing some of clustering?

Please let me know your implementation.

thanks

Re: How to display 1 million points in the Map?

SripathiRao — Wed, 27 Apr 2011 16:57:33 GMT

I am doing this by the following steps:

1) Stored procedure to get 1million record based on the spatial filter. and it returns "OBJECTID.Convert(varchar(mx),GEOMETRY)"
2) Write WCF to call this procedure and get back the result using Datareader into List<string>
3) Write a parser to parse the geometry string into ESRI.arcGIS.Client.Geometry type
4) Create Graphic with symbol and the parsed geometry
5) Add to the graphics layer.

Thanks for the reply. I have tried this, but my screen is hanging. Any other approach??

Thanks,
Sripathi Rao

Re: How to display 1 million points in the Map?

VincenzoPiscitelli — Thu, 28 Apr 2011 13:47:20 GMT

Just a question...

How would one visualize 1 million points? On a screen with a resolution of 1280x1024 you only have 1.3 million pixels. Assuming you used a graphic that was 1 pixel (which doesn't make much sense) and that the distribution of points was equal, that would saturate 77% of the screen?! Hardly useful.

Can you explain why you need to visualize so many points at one time? It might help others offer some possible solutions.

Re: How to display 1 million points in the Map?

IgressT — Thu, 28 Apr 2011 14:31:27 GMT

Just a question...

How would one visualize 1 million points? On a screen with a resolution of 1280x1024 you only have 1.3 million pixels. Assuming you used a graphic that was 1 pixel (which doesn't make much sense) and that the distribution of points was equal, that would saturate 77% of the screen?! Hardly useful.

Can you explain why you need to visualize so many points at one time? It might help others offer some possible solutions.

I have to display around 20,000 points and this is my reason why to display all the points...
Each point that I display represents that data was collected at that particular location.
As soon as the user launches my app I want to give him an overall view of where data was collected. My plan is to implement clustering.
So I have to get all the data points from SQL Server and add them to a graphics layer and implement the clustering.
My problem is how to get all the 20,000 points from the server. How to design my WCF service

Re: How to display 1 million points in the Map?

VincenzoPiscitelli — Thu, 28 Apr 2011 15:56:29 GMT

Clustering is definitely the way to go.

Getting the data via a web service should be straight forward.

Define a graphics layer in XAML and define its GraphicsLayer.Clusterer accordingly. See http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#SimpleClusterer for a sample on how to do that.

Create your WCF Web Service

Define a web method that performs the appropriate query.

Return the data as some sort of collection. You can wrap them into a custom object if you wish.

On the client, create a graphic for each point and add them to the graphics layer.

Again, refer to the sample I linked above. The overall process is the same. Except you are replacing the QueryTask with your own web service call and rather than using the geometry in the FeatureSet, you would create your own geomentry from the data returned from the web service.

Oh and 1 other thing. Returning 20,000 records x (how ever may attributes + coordinates) is going to be very verbose if you use XML. Try using a custom binding for your web service and use binaryHttpBinding. It will reduce the amount of data that gets sent over the wire.

Hope this helps.

Re: How to display 1 million points in the Map?

dotMorten_esri — Wed, 04 May 2011 01:56:51 GMT

You DO NOT want to render this client side - Cluster or not. Remember that the client will have to not only have to render them, but even worse have to download 1000000 points to the client. This is NOT going to work well.
Instead this is what the server-side rendering should be used for. There's absolutely no point in rendering all these points client-side. Only render points on the client if you know that they are going to interact with them directly using mouse hover/enter/leave. There is no app where you would expect the user to be looking at all 1 million points. Instead leave them rendered at the server, and if the user wants to query information about a specific point, use the click event and then use QueryTask to get the information about that one specific element.

I cover some of this and various tricks you can use in this session:
http://resources.arcgis.com/gallery/video/arcgis-api-for-silverlightwpf/details?entryID=E50439B8-1422-2418-88D1-E57C811A02FE (jump to 26:29)

Re: How to display 1 million points in the Map?

IgressT — Wed, 04 May 2011 12:04:58 GMT

You DO NOT want to render this client side - Cluster or not. Remember that the client will have to not only have to render them, but even worse have to download 1000000 points to the client. This is NOT going to work well.
Instead this is what the server-side rendering should be used for. There's absolutely no point in rendering all these points client-side. Only render points on the client if you know that they are going to interact with them directly using mouse hover/enter/leave. There is no app where you would expect the user to be looking at all 1 million points. Instead leave them rendered at the server, and if the user wants to query information about a specific point, use the click event and then use QueryTask to get the information about that one specific element.

I cover some of this and various tricks you can use in this session:
http://resources.arcgis.com/gallery/video/arcgis-api-for-silverlightwpf/details?entryID=E50439B8-1422-2418-88D1-E57C811A02FE (jump to 26:29)

Thanks Morton, I looked at the video and you present very interesting techniques. In my situation we don't use (or better we don't have resources) ArcGIS server. So can you suggest something that I can do on server side to render all the points and send it to the client. If you see the thread my problem is

1. I need to display 20,000 points stored on the SQL Server 2008
2. No Access to ArcGIS server
3. Each point on the map indicates some kind of data has been collected at that location and I have to give a overall view to the user to show where the data has been collected.
4. When the user zooms in to a particular location then show detailed info about the point

Re: How to display 1 million points in the Map?

dotMorten_esri — Fri, 06 May 2011 21:21:28 GMT

Sorry no. You really need a server-side component to do something like this properly. And after all this IS a client API, meaning a client to primarily ArcGIS Server. However, this might also be interesting for you: http://www.zekiah.com/index.php?q=node/146

Btw as per the license requirements (just making sure you know), AFAIK if you don't own an ArcGIS Server license, the ArcGIS Silverlight API is not free to use.

Re: How to display 1 million points in the Map?

IgressT — Sat, 07 May 2011 15:22:13 GMT

Sorry no. You really need a server-side component to do something like this properly. And after all this IS a client API, meaning a client to primarily ArcGIS Server. However, this might also be interesting for you: http://www.zekiah.com/index.php?q=node/146

Btw as per the license requirements (just making sure you know), AFAIK if you don't own an ArcGIS Server license, the ArcGIS Silverlight API is not free to use.

Thanks for the link...
I was under the impression that I can build Silverlight applications using ESRI API's even if I don't have ArcGIS server. Ok I will let my team know.

Re: How to display 1 million points in the Map?

LanceCrumbliss — Sun, 08 May 2011 14:25:07 GMT

Sorry no. You really need a server-side component to do something like this properly. And after all this IS a client API, meaning a client to primarily ArcGIS Server. However, this might also be interesting for you: http://www.zekiah.com/index.php?q=node/146

Btw as per the license requirements (just making sure you know), AFAIK if you don't own an ArcGIS Server license, the ArcGIS Silverlight API is not free to use.

out of curiosity, (we have a license, after all) where is the relevant section of the ArcGIS Silverlight API license?

Re: How to display 1 million points in the Map?

dotMorten_esri — Mon, 09 May 2011 18:03:57 GMT

You can build ESRI Silverlight API apps without a server license. However it requires it to be either be a non-commercial app, or that you buy a license.

This is described in section 3 of the license agreement:
http://resources.arcgis.com/node/agreement/1226

This also describes in more detail what "non-commercial" means. (although its all in lawyer speak 🙂

Re: How to display 1 million points in the Map?

LanceCrumbliss — Mon, 09 May 2011 18:21:04 GMT

Wow...ok. I'm glad we have a license because honestly I feel sorry for anyone looking for anything in there that would highlight the restriction mentioned above. Lawerspeak indeed! 🙂