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geoffr · 08-03-2019, 06:46

Baikal,

Thanks for sharing your world MBtiles - works nicely. Out of curiosity what Zoom levels did you use (I assume from SAS) ?

Quote:

Originally Posted by Baikal

I made MBTiles World Map with English names. Save it somewhere that anyone could download it.
https://www.dropbox.com/s/tk06j43c28...N.mbtiles?dl=0

geoffr · 08-03-2019, 06:55

Some comments on mbtiles (build 1507):

I like the left click to hide a chart, although could be a bit confusing as with other charts it brings them to the front.
It seems now when you hover on the piano bar it does not highlight the chart in the chart display in light pink as it did in previous versions
- Can we get this function back so we know which chart we are hiding when using a small display which make reading the pop-up text hard?

geoffr · 08-03-2019, 06:56

I'm looking to update OCPN to V5 on my Raspberry Pi to try it out. What is the best way to do this - compile the new or add a repository and install? (Which repository?)

thanks.

nohal · 08-03-2019, 07:15

Quote:

Originally Posted by Baksteen

Is there maybe a guide on properly preparing MBTiles files for use in OpenCPN?
I tried several software-packages to create tiles from a WMS service as well as vector data from QGIS. The main point I'm now struggling with is transparency. Is transparency supported at all? Also, what metadata is important to have?

Are there any mbtiles-datasets available already working with transparency? Would love to see them and know about the process of preparing them.

Also, please check out my file which I prepared. Zoomlevels up to 14 and transparency works in other software, except for openCPN.
https://filebin.net/k0usvztkunb7zj8n

OpenCPN is, unlike others, not too picky about the metadata and even your tileset which completely ignores the requirements of the standard (https://github.com/mapbox/mbtiles-sp...er/1.3/spec.md) we display.

Are you trying to use partial transparency?
That won't work well with OpenCPN at this moment as all the layers are blended together in a single OpenGL texture, if your ultimate goal is to make the whole tileset partly transparent, we have to do it in the code, not in the set itself. The NOAA tilesets do use transparency. Full transparency around the actual coverage area, the alpha value simply must be 0 or 255.
Values in between do not do what you expected in the current implementation as having let's say Layer 3 and 7, you will see the semi-transparent layer 3 tile AND the background through the semi-transparent layer 7 tile, while you would like to see only the background.

Vector tiles are not supported at all.

A reasonable, almost sane, metadata example (As used by NOAA, note that even they have the scheme wrong and we have to ignore it...)

Code:

profile       global-mercator
attribution NOAA
name        MBTILES_08
format       png
basename MBTILES_08
bounds      -225, 11.1784018737, -191.25, 47.0401821448
minzoom   3
version      1
template    {{#__teaser__}} <div class='tooltip'> <strong>{{name}} {{kap}} </strong> <small class='tooltip'> NTM Date: {{ntm_date}} Scale: {{scale}} Units: {{units}} {{path}} </small> </div> <style type='text/css'> .tooltip strong { display:block; font-size:16px; } .tooltip small { font-size:10px; display:block; overflow:hidden; max-height:90px; line-height:15px; }</style> {{/__teaser__}}
maxzoom  19
tilejson      2.0.0
scheme     xyz
type          overlay
description PACIFIC TERRITORIES

Pavel

Baksteen · 08-03-2019, 07:23

Thank you Pavel for the clarification.

I updated to .1507 and transparency worked (I edited my latest post afterwards..). Unfortunately, as you mentioned, it does some crazy things upon display/overlay. Maybe I can resolve most of the issues using lower zoomlevels on my export. Am running it now.

edit: No, I'm not manually adding partial transparency, but probably upon export it generalizes some of the boundaries into a softer glow. The data is more like separate points, rendered as a colored rectangle and then rasterized. On lower zoom levels, there is transparency between points. /edit

I actually went into the format specifications and just went over the 'musts'. It works, but was just curious if there's some data important for (better/efficient) rendering in openCPN.

nohal · 08-03-2019, 07:29

Quote:

Originally Posted by Baksteen

Thank you Pavel for the clarification.

I updated to .1507 and transparency worked (I edited my latest post afterwards..). Unfortunately, as you mentioned, it does some crazy things upon display/overlay. Maybe I can resolve most of the issues using lower zoomlevels on my export. Am running it now.

I actually went into the format specifications and just went over the 'musts'. It works, but was just curious if there's some data important for (better/efficient) rendering in openCPN.

You definitely should include the (correct, of course) bounds, many viewers will refuse to display your tiles without them.
We unfortunately see so many tilesets with the metadata completely wrong, that we must always check they are correct anyway so the metadata you provide will not have any effect on performance.

geoffr · 08-03-2019, 08:27

Dave,

Is it possible to make this "1000 tiles" configurable - for navigation it's fine, but when scrolling around it's rather confusing to have a large rectangle.

In the image below I have two charts in the chart group. For some reason it looks like 3 charts. The chart with low level tiles I've highlighted in yellow. The "yellow" chart shows as a rectangle, but in fact the tile set is what is shown to the right.. rather confusing.

Quote:

Originally Posted by bdbcat

Baikal...
re:
"For a set of non-free-form tiles, chart outlines were previously on tile boundaries. Now for such sets of chart outlines are rectangular."

This is a performance optimization. If a zoom level has more than 1000 tiles populated, then the coverage area is declared rectangular to the geographical extent of the tile population. Otherwise, the exact tile coverage region is used.

Thanks for the English earth.

Dave

geoffr · 08-03-2019, 08:44

Should transparency work when two mbtiles have the same zoom information? EG satellite view and chart data?

I have transparent mbtiles working well when the transparent has a higher level of zoom than another chart... but not when they are the same which is rather frustrating. (I like to use multiple satellite sources, but one chart source)

nohal · 08-03-2019, 09:23

Transparency (partial transparency to be precise) will work acceptably only if the tileset has one and only zoom level. The tilesets are covering each other in the order of their resolution (There is a problem in how the resolution is currently calculated (https://github.com/OpenCPN/OpenCPN/issues/1294), will be fixed in the next beta), from the ones that seem to have least detail to the ones that seem to have more detail (There is not much we can do to find out if our guess is right though)

geoffr · 08-03-2019, 10:00

Nohal - okay that makes sense - thanks.

Quote:

Originally Posted by nohal

Transparency (partial transparency to be precise) will work acceptably only if the tileset has one and only zoom level. The tilesets are covering each other in the order of their resolution (There is a problem in how the resolution is currently calculated (https://github.com/OpenCPN/OpenCPN/issues/1294), will be fixed in the next beta), from the ones that seem to have least detail to the ones that seem to have more detail (There is not much we can do to find out if our guess is right though)

geoffr · 08-03-2019, 10:02

In OCPN v5 the Larger/Smaller Scale Chart (CNTR_Left/Right) button is no longer available on the tool bar - can it be put back?

Also can a feature be added to use CNTR_Left/Right on mbtiles?

bdbcat · 08-03-2019, 10:58

geoffr...
re:
"For some reason it looks like 3 charts."

Does to me, too. What does the other, larger chart look like?

You would not like the performance and memory hit incurred by increasing the limit for exact tile region calculation above 1000. No plan to make it configurable. We want to support the large mainstream of users that will download shared tilesets from a huge universe of un-curated sources, without fussy configuration.

Thanks
Dave

geoffr · 08-03-2019, 13:08

I'll answer my own question

https://launchpad.net/~opencpn/+archive/ubuntu/opencpn

Quote:

Originally Posted by geoffr

I'm looking to update OCPN to V5 on my Raspberry Pi to try it out. What is the best way to do this - compile the new or add a repository and install? (Which repository?)

thanks.