topic Re: LOD - How calculate resolution? in ArcGIS API for Flex Questions

LOD - How calculate resolution?

FabianoScardua — Tue, 22 Jan 2013 10:19:32 GMT

How can I calculate the resolution (Resolution in map units of each pixel in a tile for each level.) of LOD?

I need setting the LODs for the map manually of my custom Tiled, but I don't know how calculate this value.

http://resources.arcgis.com/en/help/flex-api/apiref/index.html

Thank's for help

Re: LOD - How calculate resolution?

IvanBespalov — Tue, 22 Jan 2013 11:09:10 GMT

Tiled map service has all needed information - via this property tileInfo you can access this information in flex

Tile Info:
[INDENT]Height: 512
Width: 512
DPI: 96
[INDENT]Levels of Detail: (# Levels: 16)
Level ID: 0 [Start Tile, End Tile]
Resolution: 0,3515625
Scale: 147748799,285417
Level ID: 1 [Start Tile, End Tile]
Resolution: 0,17578125
Scale: 73874399,6427087[/INDENT][/INDENT]
...

Additional info:
find paragraph "Map Scale and Resolution:"
Mathematical relationships...

Re: LOD - How calculate resolution?

EstherColero — Sat, 11 Dec 2021 12:10:36 GMT

Hello Fabiano,

Another easy way is create a cache map service in ArcGIS Server (only the service, images are optional) with your own scales and check the rest API (like Ivan hint) or the file c:\arcgisserver\arcgiscache\<serviceName>\Layers\conf.xml.

<LODInfo xsi:type="typens:LODInfo">
    <LevelID>0</LevelID>
    <Scale>500000000</Scale>
    <Resolution>1.1897305029151397</Resolution>
</LODInfo>

Hope it helps 🙂

Regards
Esther

Re: LOD - How calculate resolution?

FabianoScardua — Tue, 22 Jan 2013 12:03:11 GMT

Thanks for responding.

Ok, but I'm creating the tiles from tilemil (tiles in sqlite) to a mobile application.

The tiles generated by tilemil not have this information.

I will use this tile in the application offline.

Re: LOD - How calculate resolution?

IvanBespalov — Tue, 22 Jan 2013 12:17:29 GMT

WebTiledLayer sample

Description:
This sample demonstrates how to add various third-party (tiled|cached)
map services to your ArcGIS API for Flex application using the WebTiledLayer class
...

Sample of extending TiledMapServiceLayer

Re: LOD - How calculate resolution?

FabianoScardua — Tue, 22 Jan 2013 14:00:24 GMT

Thanks for the reply.

I've managed to extend the class and load the tiles from a local database (sqlite). The problem is precisely the method buildTileInfo.
How can I get the values �??�??of the resolution if what you have is only png images of each tile? How to calculate this value?

I can load the tiles however they are with some error in the projection which I believe is because of the LOD.

Re: LOD - How calculate resolution?

EstherColero — Tue, 22 Jan 2013 14:37:11 GMT

I've managed to extend the class and load the tiles from a local database (sqlite). The problem is precisely the method buildTileInfo.
How can I get the values �??�??of the resolution if what you have is only png images of each tile? How to calculate this value?

I can load the tiles however they are with some error in the projection which I believe is because of the LOD.

Hi again,

I do not know how to do that, but if your application always works with the same spatial reference and LODs you can precalculate these values creating a map service with these scales in ArcGIS Server.

If you do not have one, tell me your spatial reference and LODs to help you.

Regards
Esther

Re: LOD - How calculate resolution?

YannCabon — Tue, 22 Jan 2013 17:02:34 GMT

Hi,

The resolutions of the tiles generated through Tilemill are the same as OpenStreetMap or the tile services served via arcgis.com

See the tiling scheme of the Light Gray Canvas.
http://services.arcgisonline.com/ArcGIS/rest/services/Canvas/World_Light_Gray_Base/MapServer

The resolution of the next level is the half of the current one.