Opened 9 years ago

Closed 9 years ago

#3034 closed defect (fixed)

Merk: TMS projecting wrong

Reported by: HamishB Owned by: Chris Browet
Priority: major Milestone:
Component: merkaartor Version:
Keywords: TMS Cc: samat@…



I just built the latest SVN version of Merkaartor 0.16 (r21588 according the title bar).

I am using a localhost TMS server with a GeoTiff? converted with The original GeoTiff? is available here:

(136mb ; oh why couldn't they zip it?)

In openlayers & google/yahoo/etc underneath it all looks good so I'm confident the TMS creation went ok.

Set up the URL in the Merk TMS editor, tile size = 256; 0,0 is bottom left; min = 11; max = 15; proj=epsg:900913.

(I tried min=0 as per ticket #2808 but no luck)

The overlay is some distance out, and that distance changes with Merkaartor zoom level... (screenshots attached)

? thanks, Hamish

ps- ubuntu 10.04 (in a VM)

Attachments (3)

tms_offset2.png (233.8 KB) - added by HamishB 9 years ago.
TMS mis-alignment example 2
tms_offset1.png (234.0 KB) - added by HamishB 9 years ago.
TMS mis-alignment example 1
TMS-Misaligned.jpg (240.3 KB) - added by samat@… 9 years ago.
Misaligned TMS with bottom-left origin

Download all attachments as: .zip

Change History (8)

Changed 9 years ago by HamishB

Attachment: tms_offset2.png added

TMS mis-alignment example 2

Changed 9 years ago by HamishB

Attachment: tms_offset1.png added

TMS mis-alignment example 1

comment:1 Changed 9 years ago by HamishB

loading the source image as a GeoTiff? background with the GDAL plugin works perfectly.

comment:2 Changed 9 years ago by Chris Browet

Seems typically to indicate a wrong min zoom.

Did you try doing -1 or +1 to to the min zoom?

If that do not work, can you make your tiles available thru the net?

comment:3 Changed 9 years ago by SamatJain

Cc: samat@… added

I think I can confirm; this only appears to happen when using TMS with "Origin is bottom-left" as the original reporter is using.

I created a set of tiles with The output is in TMS standard layout (bottom-left origin). They are here:

For compatibility with older versions of Merkaartor/Potlatch?, I had written a script that renames tiles from bottom-left origin to top-left origin layout (used by Google, OSM, and older versions of Merkaartor). Those tiles are located here:

If you browse to the area:

You'll notice that the first set of bottom-left origin tiles is misaligned, while the second set with a top-left origin is aligned correctly. The zoom level looks fine, it just looks as if bottom-left has an off-by-one error in a calculation somewhere shifting everything down. Setting minimum zoom to 0 has no effect. I've attached a screenshot of the display.

Both tile sets are tile size 256, min zoom 7, max zoom 17, projection EPSG:900913. I am using Merkaartor 0.16.1 from Debian experimental.

Changed 9 years ago by samat@…

Attachment: TMS-Misaligned.jpg added

Misaligned TMS with bottom-left origin

comment:4 Changed 9 years ago by Chris Browet

Owner: changed from cbro@… to Chris Browet
Status: newassigned

Thanks for the very detailed description.

Unfortunately, it seems that I cannot reach

comment:5 Changed 9 years ago by Chris Browet

Resolution: fixed
Status: assignedclosed

Solved in Git.

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