[fixed] Missing tiles at zoom level 16

[ukuest]

Hi,
I am preparing maps for a planned 300 km hike.
Source is Outdooractive.com maps (Germany). This map is special in that it is a vector map up to level 15, but level 16 is a real topographical (raster) map (looks like 1.25.000), so it is ideal for hiking.

In general, no problem with Alpinequest. Maps up to 400-500 MB load quick enough on my Galaxy S, and work without problems.

BUT: some tiles at level 16 are missing.

Now I do not know if this the fault of Map Creator or the fault of AlpineQuest, and due to the flat file map format I cannot check the file directly.
Map Creator gives no error message and completes the maps successfully.

This has happened with several maps.
These are not tiles at the border, but straight in the middle of the area.

I know what I could do to do more testing: e.g. building a TrekBuddy map from the same tile cache, and checking the same tiles in TrekBuddy; or redownloading and building the same map for AlpineQuest and checking whether the same tiles are missing...)

But with maps of 10.000s of tiles this would be laborious.
So I am asking whether this is a known problem, and if there are any suggestions?
Any help appreciated.

ukuest

[ukuest]

I prepared another (smaller) map from the already downloaded tiles.
Now the tiles that were missing before are displaying in AlpineQuest.
So they definitely have been downloaded by Map Creator.

But that still does not tell me whether the mistake is in Map Creator or in AlpineQuest.

ukuest

[Psyberia-Support]

Hi,
I don't know especially Outdooractive.com, but I know that for OpenStreetMap (Cycle map for instance) such behavior is current.

This is due to the fact that OSM server do not pre-create image tiles. When someone is visiting a location where tiles are not created, the server put them in a rendering queue (tiles are not necessary created immediately). It can be a long time (fiew seconds, depending on the rendering queue size, the server capabilities) between the moment you visit the map and the moment the tiles are rendered. When you use a browser you just need to refresh the page, but if you use a tool like the map creator, you'll need to recreate the map.

This is done in order to avoid rendering all the world, including part that will never be visited. Rendered tiles are kept one week and are then re-created at next visit.

I'll have a look at Outdooractive.com, but considering your explanation of the problem is sounds like something similar.
Regards

[ukuest]

Thank you for the explanation. But I don't think it fully explains the missing tiles.

I have now done the following tests:
In Mobile Map Creator, I have zoomed to level 16, and scrolled through 50-70 kms along the itinerary, so that MOBAC had to load each of those tiles at zoom 16, and I could see those tiles rendered correctly on the screen. Then I created the maps from those areas.

And again, in both maps I created like this, many of the zoom 16 tiles are missing in AlpineQuest.

Map sizes (AQM files) were 90 and 200 MB, so they are not excessively large.

I have the suspicion that it is a bug in the modification of Atlas Creator for the AQM format. But whether it is the map creation or the rendering in AlpineQuest - the result for me is the same: I cannot get the Outdooractive.com maps that I want to use into AlpineQuest. I do not know what else I could try.

ukuest

[Psyberia-Support]

OK I didn't understand that your missing tiles were correctly rendered on MOBAC, meaning that tiles have been correctly rendered.
So as you say it comes from the writing or from the reading of the map format.
I'll have a look as soon as possible (I'll try this evening) and let you know what I could do.

[ukuest]

Thank you for looking into it.
I really prefer AlpineQuest over the other mapping apps.
Would be a pity if I could not use it.

[Psyberia-Support]

I made some tests this WE and didn't reproduced the problem.
I chose Outdooractive.com Germany, selected level 15 (and not the 16 on order to not preload tiles), selected an area (in schwarzwald), checked level 16 and created the map.
All tiles were saved/displayed. I used Map Creator 1.7.2.AQM.
I also created a map with pre-loaded tiles. Again it was OK.
Can you indicate me the approximative location you used ?

[ukuest]

Ok. Did some more testing too. Yesterday I have been able to reproduce the same problem with a map/atlas generated on a different computer.

Here is what I did:

1. map/atlas (reproduced)
Choose Outdooractive.com (Germany only).
Use zoom levels 8-16 (all levels except 17).
Find the cities Eisenach-Gotha-Erfurt (approx. in the middle of Germany).
Draw the map rectangle so that Eisenach is included in the left side and and Erfurt is included on the right side. In the vertical dimension the northern and southern city limits of Erfurt are included fully (best seen at zoom level 10).
What you get is a narrow horizontal strip. On a grid zoom of 13 on the main display, the map will be about 5 tiles high and 20 tiles wide.
Now create the atlas and copy to device. AQM file size should be around 100 MB.
In AlpineQuest, open the map in the lowest resolution. Center on the city of Erfurt (right side of map). Now zoom in.

What I see is that I can get only zoom level 15.
Now scroll to the west. After a few kilometers, outside Erfurt city, at some point the gray + sign will turn darker and zoom level 16 will be available there.

2. map/atlas
Try the area between Siegen and Marburg, include Siegen on the left side, Marburg is included in the lower right corner, at the top of the map go up to Frankenberg/Eder. At grid zoom 13, this will be about 10 tiles high and 19 tiles wide, resulting in a AQM file of around 200 MB.

Open in AlpineQuest at lowest zoom, center on Marburg, zoom in.
Now with this map, I mostly see the same thing: no zoom level 16 available in Marburg, only up to 15. Level 16 starts becoming available somewhere to the west. But I think (not totally sure) I have also opened this map once and did see zoom 16 levels in Marburg, but this time there was a vertical area with missing zoom 16 tiles somewhere west of Marburg, more towards the center of the map.

This sounds crazy, I know.

I hope you can reproduce it now.
It looks like at certain map dimensions vertical strips of highest zoom level tiles get lost.
If you want, I can also put up a defective map on web space somewhere so you can download it. But they are 100 MB.

Good hunting!

ukuest

[Psyberia-Support]

Thanks for this clear and detailled explanation.

I have reproduced the problem!
I also found what's wrong. It's actually a feature of MOBAC which can automatically split big maps is smaller ones (some MOBAC atlas formats do not support big maps). You can see it before creating the map: in the tree view, you have one entry per level except for the level 16 which has 2 entries, "level 16 (0)" and "level 16 (1)".
The problem is that AQM format doesn't handle this feature correctly and only the first splitted map is taken into account (making an area missing).

You can de-activate this feature in the AQM Map creator: Settings -> Map Size. Add a zero at the end of the default value (set "327670" for exemple).
This feature is useless because AQM maps are not area limited.

I'll change this in the new version of the Map Creator.
Thanks for pointing me out this bug, and I'm really sorry for the time you've lost because of it...

I re-created the map after having change the parameter and Erfurt is now visible for level 16 (and the level count is also correct).
Tell me if that's also OK for you,
Regards

[ukuest]

That is wonderful news!
I am delighted that you could find the problem so soon.
Yes, that explanation sounds entirely plausible.
I'll test my map areas again and will let you know soon.

Thanks for looking into this!

[ukuest]

It works!
Generated one map so far, no tiles missing anymore. Great!

I suppose just adding a zero to file size will not work if my maps get too big, but that is not serious. I can wait for the fix to MOBAC/AQM.

Merci beaucoup!

ukuest

[Psyberia-Support]

OK that's great.
Merci à toi, for helping me with this issue!

[New User]

Had the same problem (1.8 Beta), when the map creator splits a map over 2 or more AQM files for a specific zoom level, (usually 16 or 17 for me), it overwrites 16(0) with 16(1) etc.etc. so you only end up with one map for each zoom level - the last piece it created.

I ended up pausing the creator when it had written a map piece to disk and re-named the created AQM file by adding a 0,1,2 etc. at the end of the filename. Then un-pause the creator and repeat untill all map parts were created. Problem solved but results in too many maps and looks messy in AQ menu.

Please bring in support for AQM v2 maps soon

Great App

[Psyberia-Support]

Hi,
The workaround right now is to change the maximum map size setting in the Map Creator (or in MOBAC).

The MOBAC 1.8 beta 1 only supports AQM v1 map, and has this issue.

The MOBAC 1.8 beta 2 will support AQM v2 and the issue is corrected (levels are still splitted according to the max map setting but when creating the AQM map they are joined in one layer again).
Files are already pushed on the MOBAC svn, I'm just waiting for the beta 2 build.

Regards