UTM to Latitude and Longitude

[MichaelAquilina]

Hi everyone, id really appreciate some help understanding how to place the data in these shape files onto the ArcGIS control. The values are in utm but the ArcGIS control with Bing Imagery uses Web Mercator (i assume these are not the same?)

Also, is there some form of way of placing objects over the map without using a canvas?

Thanks in Advance!

[IgressT]

Hi everyone, id really appreciate some help understanding how to place the data in these shape files onto the ArcGIS control. The values are in utm but the ArcGIS control with Bing Imagery uses Web Mercator (i assume these are not the same?)

Also, is there some form of way of placing objects over the map without using a canvas?

Thanks in Advance!

There might a better way but I did the same kind of thing in my current project by using the geometry service.
The service has a Project method that accepts list of graphics that needs to be projects along with in spatial reference and out spatial reference.

[MichaelAquilina]

There might a better way but I did the same kind of thing in my current project by using the geometry service.
The service has a Project method that accepts list of graphics that needs to be projects along with in spatial reference and out spatial reference.

Hi and thanks for your reply

I have found out how to add items over the map, however i am now having some difficulty with projections. I am trying to get to place TIGER road vector data over the ArcGIS control which is using Bing Aerial Imagery. I am using GeographicToWebMercator() on each point found in the shape file to convert it from unprojected lat long to mercator projection, however this is horribly displaced and wont be of much use this way. Is there some better method that i am not aware of? Or is it something i cannot avoid?

I am using to data found on ArcGIS site:
http://arcdata.esri.com/data/tiger2000/tiger_download.cfm

[DominiqueBroux]

From your first post, the coordinates are in UTM. In this case GeographicToWebMercator doesn't help and the only option is the geometry server (or to write by yourself the conversion code at the client side)

[MichaelAquilina]

From your first post, the coordinates are in UTM. In this case GeographicToWebMercator doesn't help and the only option is the geometry server (or to write by yourself the conversion code at the client side)

Hi, it is true that in my first post i was using data in UTM, however i have now changed to using TIGER vector data which seems to be in unprojected latitude and longitude (see the link i sent).

I cant seem to find this geometry server, is it in the library reference? How and what exactly is it used for? Sorry for my lack of knowledge in this area, but im still kind of new 😕

Thanks!

[DominiqueBroux]

There is a sample on how to use a geometry server for projecting coordinates : http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#Project

But, if your coordinates are geographical, you should not need a geometry server. 'GeographicToWebMercator' should work.
Try debugging the input and the output values of GeographicWebMercator. This could give a clue.

For example, it might happen that the coordinates are reversed (Latitude/Longitude instead of Longitude/Latitude).

[MichaelAquilina]

There is a sample on how to use a geometry server for projecting coordinates : http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#Project

But, if your coordinates are geographical, you should not need a geometry server. 'GeographicToWebMercator' should work.
Try debugging the input and the output values of GeographicWebMercator. This could give a clue.

For example, it might happen that the coordinates are reversed (Latitude/Longitude instead of Longitude/Latitude).

well thats the method im using for converting the values and it still seems to give me offset results. The shape and topology of the vectors are correct but they do not "align" well with the imagery which gives me the impression i am doing something wrong in terms of a projection.

Could someone do me a huge favor and confirm for me whether the coordinates used in the TIGER files are geographic coordinates? Are they stored under some projection that i am no aware of? ( i cant seem to find a .prj file with the shape files so i assumed they were unprojected)

[IgressT]

well thats the method im using for converting the values and it still seems to give me offset results. The shape and topology of the vectors are correct but they do not "align" well with the imagery which gives me the impression i am doing something wrong in terms of a projection.

Could someone do me a huge favor and confirm for me whether the coordinates used in the TIGER files are geographic coordinates? Are they stored under some projection that i am no aware of? ( i cant seem to find a .prj file with the shape files so i assumed they were unprojected)

If its of any help you have to DEFINE a projection to the Tiger files before using them.

[MichaelAquilina]

If its of any help you have to DEFINE a projection to the Tiger files before using them.

wouldnt making use of the GeographicToWebMercator() method handle this on its own?

[DominiqueBroux]

At this time, my best bet is still that you reversed the coordinates (Latitude/Longitude instead of Longitude/Latitude).
Did you check this point?

Can you share how look the input coordinates when you call 'GeographicToWebMercator'?