Changing Map Projections

[HannahLuedeke]

Hi, I've just downloaded the ESRI Flex Viewer, and I am trying to make the viewer switch between Mercator and polar projections. I have been searching on Google for quite some time, and can't seem to figure out how to do it. I've found information about spatial reference and wkid, but changing the wkid (in the extent tag under the Map) doesn't do anything to the map. It is still flat.

So, does this mean that the map itself has to be in polar already? If not, how to I change my projection?

I know this is broad, but I am new to this and can't seem to get a foothold anywhere. Thanks!

[philippschnetzer]

By default, the Viewer is set to take whatever projection the first basemap is set to under the <basemaps> tag in config.xml.   Make sure your <initialextent> and <fullextent> coordinates match the projection coordinates of your first basemap in the <basemap> list.  So, you have a couple of options.  Stcik with the standard web mercator projection so that you can use all of Esri's basemaps and then either project-on-the-fly your data, or reproject your data first to web mercator.  Or, create your own basemap in Polar, but then if you would like to use Esri's basemaps you would have to project their tiled imagery on the fly (type="dynamic") - this will not be very efficient.

[HannahLuedeke]

So the first option - on-the-fly data projection - does this still mean I can view the map in polar? My ultimate goal here is to see a map that is centered on the North (or South) pole and having the concentric circle representing latitude. If I can achieve this through the first, more efficient option, then obviously I'd like to. But I will do whatever it takes to get the polar view of the map.

That being said, I need an example, or at link to a reference, or...something. I've seen many forums discussing the theory of how to do this (much like you did), but consider me a super beginner. I have no idea how to project on-the-fly data or where to even start.

Thanks for all your help!

[philippschnetzer · Accepted solution]

Here's a good starting point:  http://help.arcgis.com/en/webapps/flexviewer/help/index.html#/Main_configuration_file/01m30000001800......read this over...there's good info in there.

I don't think that Esri's (or google or bing for that matter) web mercator basemaps represent the polar regions all that well...lots of distortion...That being said, you will likely need to create your own basemap in ArcGIS Desktop which shows the area of interest the way you want. If you then need to incorporate existing Esri basemaps into your app you only have the option to project Esri's basemap(s) on the fly - since they are in the web mercator projection.  This means instead type="tiled" you will need to use type="dynamic".  Doing this you can project Esri's basemap into any projection you wish, but with a performance hit of course.  Also, not 100% sure about this one but you might need to put the following in as well:  dpi="120", or else the projected basemap will come in looking grainy/pixelated.