[OpenLayers-Users] Using Openlayers with Tile and Export Image doesnt "overlap"

[RajeevSharma]

Many thanks for the response Christopher. 
I am sorry, since I am unable to share the map service as it is outside the
public network. 

I am able to get the max extents easily, however, I am unable to find out
which resolution value to take. 

As an example , say I have 3 layers which are cached. The images are 512 by
512 pixels. 
max Extents are (-180, -90, 180, 90). 

Layer 1 - Resolution 1058.33
Layer 2 - Resolution 529.16
Layer 3 - Resolution 132.29

I had read in the news group the max resolution should be something like
(Max (Xmax - Xmin), (Ymax - Ymin))/512, is this correct?

- Thanks in Advance,
Rajeev




Christopher Schmidt-2 wrote:
> 
> On Thu, Aug 13, 2009 at 05:05:18AM -0500, RajeevSharma wrote:
>> 
>> Hello, 
>> I am using Open Layers for the first time, and would like to display maps
>> from multiple services. 
>> 
>> 1. A Tiled map service which forms the background. 
>> 2. One or more Dynamic map services which will be used to overlay on top
>> of
>> the first service. 
>> 
>> I am using the XYZ and ArcGIS93Rest respectively to do the same. The maps
>> do
>> display but their images arent synchronised. Meaning, the tiled layer
>> image
>> comes up on the top left part of the screen, and the export map from the
>> Rest service comes up in the centre and larger than the tiled map.
>> 
>> I tried tweaking around with the resolution param which didnt help much.
>> The
>> maps moved a bit closer until 4000 then they started moving apart.
>> Setting
>> this to "auto" didnt help either. The SRS is the same for both services.
>> As
>> are the map initial and final extents. 
>> 
>> Can any one please let me know if I am doing something wrong out here?
> 
> the XYZ layer requires you to have correct maxExtent and maxResolution
> properties matchingthe grid set up in the tile cache creation
> configuration.
> Without this information, they will not line up. Your Tile Cache metadata
> may provide this information, or you may need to consult some othr
> resource
> to find it. Sharing a link to the tiles you are trying to use, as well as
> the code you are using to try to use thm, may be helpful.
> 
> Best Regards,
> -- 
> Christopher Schmidt
> MetaCarta
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> Users at openlayers.org
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> 
> 

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