Re: [OSM-dev] Retina tiles - best way to support them?
On 17.07.2012 20:25, Robert Joop wrote: But I’ve copied your page, adjusted the style and tiles URIs and added a viewport. As expected, it doesn’t make any visible difference on an iPhone 3 (pixel ratio 1), but the difference is remarkable on e.g. an HTC Sensation (pixel ratio 1.5) or an iPhone 4 (pixel ratio 2). See https://mlist.timesink.de/osm-geofabrik-highres/ for some screen shots. That looks amazing! Can the index.html be reached somehow to see the result on my own devices? Peter ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
[Since I kicked off this branch of the thread, I take the liberty of following up even though two weeks have passed, due to vacation.] On 12-07-05 09:44:25 CEST, Frederik Ramm wrote: On 06/27/2012 01:10 AM, Robert Joop wrote: 3. Modify style as per 1., double size of meta tiles to 4096x4096, and double size of tiles to 512x512. This avoids the increase in font nastiness *and* it has the nice effect that one Retina tile at a certain zoom level shows exactly the same content as a normal tile, just on 512x512 instead of 256x256 and therefore at twice the resolution. It would, however, require clients (OpenLayers et al.) to work with the larger tile size. This option sounded best to me as well. I just tried this out and found that, on a standard non-mobile Firefox browser, OpenLayers displays the new 512x512 tile just fine, it scales it to 256x256 in the browser. I can then use the browser's zoom function to blow up the OpenLayers display and while everything becomes jaggy when I do this with normal tiles, the map still looks nice when using the double resolution tiles. Does this mean that it would be an acceptable viewing experience for mobile users as well? Most likely, I’d guess. I’d like to try it on some devices with pixel ratio 1, like the Nexus One with its penTile display http://en.wikipedia.org/wiki/Nexus_One#Hardware or the iPhone 4. Is your test setup publicly accessible? It is now, here: http://mull.geofabrik.de/hires.html By default this will come up with standard Mapnik tiles from osm.org, but you can switch to my hires tiles in the layer switcher. If I do this in Firefox on my desktop machine, there's hardly any difference between the two, as OL downscales the images from 512x512 to 256x256 for display. Only if you right-click on an image will you see that it is indeed bigger than normal. I'd be interested in hearing from users of high-resolution displays if these big tiles actually make a difference (except being slower to load...). With your page on e.g. an iPhone, the two sets of tiles look identical, but that’s because its a huge page squeezed onto the tiny display, so even the standard tiles have far too high resolution. And one cannot zoom into the page as the gesture is caught by openlayers for zooming into the map. But I’ve copied your page, adjusted the style and tiles URIs and added a viewport. As expected, it doesn’t make any visible difference on an iPhone 3 (pixel ratio 1), but the difference is remarkable on e.g. an HTC Sensation (pixel ratio 1.5) or an iPhone 4 (pixel ratio 2). See https://mlist.timesink.de/osm-geofabrik-highres/ for some screen shots. rj ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
On 05.07.12 09:44, Frederik Ramm wrote: It is now, here: http://mull.geofabrik.de/hires.html Looks gorgeous! Side by side comparison: http://www.openstreetmap.at/userfiles/vergleich.png Now the icons should also be retinated... ;) BTW, it is impossible to touch the current OpenLayers elements on an iPhone 4S. Isn't there a mobile OL style available? I'm looking forward to printing an A0 size poster of this... :) /al ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
On Jul 6, 2012, at 1:00 AM, Andreas Labres wrote: On 05.07.12 09:44, Frederik Ramm wrote: It is now, here: http://mull.geofabrik.de/hires.html Looks gorgeous! Side by side comparison: http://www.openstreetmap.at/userfiles/vergleich.png Now the icons should also be retinated... ;) The stylesheet should move to use svg icons, which Mapnik = 2.x supports. Dane ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
Hi, On 06/27/2012 01:10 AM, Robert Joop wrote: 3. Modify style as per 1., double size of meta tiles to 4096x4096, and double size of tiles to 512x512. This avoids the increase in font nastiness *and* it has the nice effect that one Retina tile at a certain zoom level shows exactly the same content as a normal tile, just on 512x512 instead of 256x256 and therefore at twice the resolution. It would, however, require clients (OpenLayers et al.) to work with the larger tile size. This option sounded best to me as well. I just tried this out and found that, on a standard non-mobile Firefox browser, OpenLayers displays the new 512x512 tile just fine, it scales it to 256x256 in the browser. I can then use the browser's zoom function to blow up the OpenLayers display and while everything becomes jaggy when I do this with normal tiles, the map still looks nice when using the double resolution tiles. Does this mean that it would be an acceptable viewing experience for mobile users as well? Most likely, I’d guess. I’d like to try it on some devices with pixel ratio 1, like the Nexus One with its penTile display http://en.wikipedia.org/wiki/Nexus_One#Hardware or the iPhone 4. Is your test setup publicly accessible? It is now, here: http://mull.geofabrik.de/hires.html By default this will come up with standard Mapnik tiles from osm.org, but you can switch to my hires tiles in the layer switcher. If I do this in Firefox on my desktop machine, there's hardly any difference between the two, as OL downscales the images from 512x512 to 256x256 for display. Only if you right-click on an image will you see that it is indeed bigger than normal. I'd be interested in hearing from users of high-resolution displays if these big tiles actually make a difference (except being slower to load...). Feel free to play with these tiles (tile URL is e.g. http://mull.geofabrik.de/osm2x/6/33/21.png), but note that this is a play server that may or may not be working, and is likely to be slow (currently pre-rendered only up to z11), and also I'll probably drop this tile set in a few weeks so if you read this in a mailing list archive later the link will be dead. Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09 E008°23'33 ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
2012/7/5 Frederik Ramm frede...@remote.org: I'd be interested in hearing from users of high-resolution displays if these big tiles actually make a difference (except being slower to load...). actually it doesn't make any difference on an iPhone4 (960x640px), I guess at least with this particular OL settings they are displayed at 50% like on your desktop. Btw.: the tiles are NOT identical also apart from the resolution, look e.g. at Fürth: on the normal tiles there is Erlangen above it, while on the hires tiles it isn't. On the other hand it wouldn't even be desirable (IMHO) to have the exact same tile at a higher resolution. To make best benefit from more pixels on the display it would be ideal to have a dedicated style to be able to get more details on the same zoom level. Something in between the detail level of the normal style (currently too small) and the next zoom level would be nice (so you wouldn't only get a crisper view but also slightly more detail). Another thing is that on mobile devices traffic and loading speed are often an issue, and upscaled images (standard tiles at 200%) are generally sufficient for most users I guess, with the benefit of fewer data to be transfered (and cached!). Especially when it comes to offline tiles of bigger areas the increase in memory consumption of those hires tiles is significant (around 3 times on a rough estimate with your tiles). To overcome these issues rendering on the device could be a solution (not sure what this means in terms of increased battery consumption), or maybe a hybrid approach (hillshading and contours / area fills prerendered, overlayed with vector roads and pois). This would even lead to a native stepless zooming experience (like a WMS), and the vectors could maybe be used for other things as well (routing (?), feature search and highlighting). cheers, Martin ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
Hi, On 07/05/2012 10:32 AM, Martin Koppenhoefer wrote: Btw.: the tiles are NOT identical also apart from the resolution, look e.g. at Fürth: on the normal tiles there is Erlangen above it, while on the hires tiles it isn't. Yes, but that's just normal style idiosyncracies - whatever comes first is rendered first, it's more or less random. On the other hand it wouldn't even be desirable (IMHO) to have the exact same tile at a higher resolution. To make best benefit from more pixels on the display it would be ideal to have a dedicated style to be able to get more details on the same zoom level. Probably depends on just *how* much bigger your resolution is. Another thing is that on mobile devices traffic and loading speed are often an issue, and upscaled images (standard tiles at 200%) are generally sufficient for most users I guess Sure. When CloudMade launched their tile service a while ago, they even offered a special mobile style designed to produce tiles that use less space, and I believe they even cut tiles to 64x64 or so in order to reduce unnecessary downloads. It is clear that double-resolution tiles like the ones I made here are a luxury that only those with lots of bandwidth and storage space will want to afford. To overcome these issues rendering on the device could be a solution Yes, I think rendering on the device is certainly the future, and bitmap tiles will probably be phased out in a couple of years, except maybe for overview maps on very low zoom levels. This would even lead to a native stepless zooming experience (like a WMS), and the vectors could maybe be used for other things as well (routing (?), feature search and highlighting). All of that is already available in commercial applications like Skobbler's ForeverMap today and there are already promising Open Source in-browser rendering engines so it's pretty clear that this is where the journey goes. I'm not making high-resolution tiles as a replacement for vector rendering - just as an interim solution until vector rendering for the masses is actually here. Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09 E008°23'33 ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
Am 05.07.2012 09:44, schrieb Frederik Ramm: Hi, On 06/27/2012 01:10 AM, Robert Joop wrote: 3. Modify style as per 1., double size of meta tiles to 4096x4096, and double size of tiles to 512x512. This avoids the increase in font nastiness *and* it has the nice effect that one Retina tile at a certain zoom level shows exactly the same content as a normal tile, just on 512x512 instead of 256x256 and therefore at twice the resolution. It would, however, require clients (OpenLayers et al.) to work with the larger tile size. This option sounded best to me as well. I just tried this out and found that, on a standard non-mobile Firefox browser, OpenLayers displays the new 512x512 tile just fine, it scales it to 256x256 in the browser. I can then use the browser's zoom function to blow up the OpenLayers display and while everything becomes jaggy when I do this with normal tiles, the map still looks nice when using the double resolution tiles. Does this mean that it would be an acceptable viewing experience for mobile users as well? Most likely, I’d guess. I’d like to try it on some devices with pixel ratio 1, like the Nexus One with its penTile display http://en.wikipedia.org/wiki/Nexus_One#Hardware or the iPhone 4. Is your test setup publicly accessible? It is now, here: http://mull.geofabrik.de/hires.html By default this will come up with standard Mapnik tiles from osm.org, but you can switch to my hires tiles in the layer switcher. If I do this in Firefox on my desktop machine, there's hardly any difference between the two, as OL downscales the images from 512x512 to 256x256 for display. Only if you right-click on an image will you see that it is indeed bigger than normal. You may simply zoom in in Firefox using Strg++ to see the benefit ;) regards Peter ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
On Thu, Jul 5, 2012 at 9:44 AM, Frederik Ramm frede...@remote.org wrote: If I do this in Firefox on my desktop machine, there's hardly any difference between the two, as OL downscales the images from 512x512 to 256x256 for display. Only if you right-click on an image will you see that it is indeed bigger than normal. Actually, the text rendering does look better even on the desktop, especially on very small texts. But I guess you could achieve the same effect by downsampling the tile on the server side, without the need for transmitting 512x512 tiles. Igor ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
Hi, FWIW, Maperitive provides a resolution parameter to its generate-tiles command. The parameter is an integer value indicating the scale to use when rendering tiles - the default 1 renders 256x256 tiles. If you set it to 2, you get 512x512. Technically the whole thing is implemented by scaling the graphics, which is quite easy to do in GDI+ (.NET graphics engine). The user doesn't have to change the map style. I used the same technique to achieve the subpixel accuracy in Maperitive (since GDI+ doesn't provide for this): http://braincrunch.tumblr.com/post/13459650973/maperitive-beta-subpixel-accuracy Best regards, Igor On Tue, Jun 26, 2012 at 11:05 PM, Frederik Ramm frede...@remote.org wrote: Hi, I have had some people asking whether I could supply them with Retina map tiles. Retina is an Apple brand name for higher resolution displays, and these users tend to mean tiles with twice the resolution. I wonder if anyone has done this already. I can think of a number of possible angles to attack this: 1. Double all font sizes, line widths, etc. in the Mapnik style file (recent Mapnik versions also have a built-in scaling option that achieves about the same) and adapt all scale denominators accordingly. This would mean that meta tile size, tile size, and everything else would remain unchanged but you'd be shifting everything by one zoom level - what was on one z16 tile before is now on four z17 tiles. The Retina user would see less detail on the same zoom level and therefore would have to go down to z19 to see what is currently shown on 18. Also, font nastiness along the metatile edges would increase; the amount of font nastiness depends on the ratio of tile size to font size, so doubling font sizes and keeping metatile sizes will increase label clipping and other strange things. (Simply increasing the buffer doesn't help.) 2. Modify style as per 1., but also double the size of meta tiles to 4096x4096. Cut 16x16 normal tiles out of one meta tile, rather than 8x8. This avoids the increase in font nastiness but requires internal processes to adapt to larger metatiles. The zoom level shift problem is the same as in 1. 3. Modify style as per 1., double size of meta tiles to 4096x4096, and double size of tiles to 512x512. This avoids the increase in font nastiness *and* it has the nice effect that one Retina tile at a certain zoom level shows exactly the same content as a normal tile, just on 512x512 instead of 256x256 and therefore at twice the resolution. It would, however, require clients (OpenLayers et al.) to work with the larger tile size. Your thoughts on these options - are there more than these three, perhaps? - would be most welcome. (Tiles for printing is a very similar issue - print users tend to want quad-resolution tiles, and again you have the options of shifting the zoom level by 2 or making 1024x1024 tiles.) Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09 E008°23'33 __**_ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.**org/listinfo/devhttp://lists.openstreetmap.org/listinfo/dev ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On 27-06-12 23:12, Robert Joop wrote: Why unreadable? What viewport setting do you use? A mapquest widget is used within a native app. angles I didn't saw you comment on was: going svg.gz all the way. Rendering tiles in SVG, doing so with a clue, for example fixed poit coordinates allows a decent compression over an easy zoom. How good is the SVG support on mobile devices? http://en.wikipedia.org/wiki/Scalable_Vector_Graphics#Mobile_profiles What about devices without decent SVG support? Serve legacy PNG available at fixed resolutions. Do you want to have two rendering pipelines, one SVG for higher pixel ratios and one PNG for less capable devices/browsers? Yes, don't break what ain't broken, and introduce a new better way that is slowly adopted. Stefan -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.18 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEAREKAAYFAk/sj9YACgkQYH1+F2Rqwn1g4gCghwBGrr/F843P8LO2gqOxaSqp vh8AnAk9t8VpC4pWuZ3vzaRemXuTCYWG =M6if -END PGP SIGNATURE- ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
Hi, On 06/27/12 02:52, Paul Norman wrote: I did some work on this for print where I wanted to print 1200 DPI maps. I found that with one exception, everything just worked if I created a mapnik.Image of the higher resolution and used an appropriate scale factor. https://github.com/pnorman/mapbook/blob/master/mapbook.py#L201 is the relevant section of the code. Unfortunately I haven't had time to work on it lately. For my normal printing needs, I always produce SVGs with nik2img and then have them rasterized at higher resolution. Of course the cost is blocky PNG icons. TBH I'd prefer Mapnik to produce large but blocky PNGs when using a scale factor 1 - this becomes doubly important in the case of the ShieldSymbolizer where you'd want your font to fit in the shield provided, which isn't the case with PNG shield icons and scaling at the moment. What I would suggest is a version of osm.xml which uses SVG icons instead of PNG icons, allowing for use at any resolution. That would of course be ideal. Some, but not all, icons used in the standard OSM style are PNGs made from SVG already. Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09 E008°23'33 ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
Frederik Ramm frede...@remote.org wrote: Your thoughts on these options - are there more than these three, perhaps? - would be most welcome. Hm, I consider this to be a renderer rather than a stylefile issue. On Mapserver (which is unpopular in the OSM world for some reason) there is are two options for this: RESOLUTION and DEFRESOLUTION. Imagine you have a Style designed for desktop screens like most styles and you want to go for a 200 DPI Output resolution you can simply put the following into a mapfile: RESOLUTION 200 DEFRESOLUTION 96 (defaults to 72) http://mapserver.org/mapfile/symbology/construction.html#symbol-units I think something like this should also be implemented in Mapnik, at least in the long run. Regards Sven -- A strategy for rewarding artists that regulates 'copies' makes as much sense in the digital age as a strategy for controlling greenhouse gases that regulates breathing. (Lawrence Lessig) /me is giggls@ircnet, http://sven.gegg.us/ on the Web ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
On 27 June 2012 06:22, Paul Norman penor...@mac.com wrote: The one exception to it just working is png POI graphics. These appear at a reduced scale with mapnik's AGG renderer and at the same scale but blocky with the mapnik cairo-based PDF renderer. This is an inherent limitation of bitmapped graphics - it either looks tiny or it looks bad. Fonts and line widths worked perfectly. What I would suggest is a version of osm.xml which uses SVG icons instead of PNG icons, allowing for use at any resolution. Even I tried playing out with both mapnik and osmarender . In osmarender it uses the default SVG but the style was not that easily scalable. Mapnik default would do better with SVG . Anyways Mapquest already uses SVG in its style as per https://github.com/MapQuest/MapQuest-Mapnik-Style/tree/6f7ea2723c07a1db2d17c2336dd3a0b3dd2d6fe9/mapquest_symbols Regards, Pavithran -- pavithran sakamuri http://look-pavi.blogspot.com ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On 26-06-12 23:05, Frederik Ramm wrote: I have had some people asking whether I could supply them with Retina map tiles. Retina is an Apple brand name for higher resolution displays, and these users tend to mean tiles with twice the resolution. I am glad that Retina raises the issue, that is already present on Android, high resolution displays make the map unreadible. One of the angles I didn't saw you comment on was: going svg.gz all the way. Rendering tiles in SVG, doing so with a clue, for example fixed poit coordinates allows a decent compression over an easy zoom. The higher the DPI the more bandwidth is required to serve the tiles anyway, there must be some threshold where it is really more worthwile to render in whatever GL standard on the client, than sending over bitmaps as (effectively as textures). Stefan -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.18 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEAREKAAYFAk/rP/wACgkQYH1+F2Rqwn3e0ACfZiFsvNudHwzFFPkvxnLbHi2s qPcAn3mviG0dSB6mqH5r6W5e5KVRP5h0 =f0jy -END PGP SIGNATURE- ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
On 12-06-27 19:16:44 CEST, Stefan de Konink wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On 26-06-12 23:05, Frederik Ramm wrote: I have had some people asking whether I could supply them with Retina map tiles. Retina is an Apple brand name for higher resolution displays, and these users tend to mean tiles with twice the resolution. I am glad that Retina raises the issue, that is already present on Android, high resolution displays make the map unreadible. One of the Why unreadable? What viewport setting do you use? For example, when you use the same viewport width 320 on both iPhone and iPhone 4, then the map looks the same on both devices, right? It’s just that it doesn’t look as crisp as could be on the iPhone 4. angles I didn't saw you comment on was: going svg.gz all the way. Rendering tiles in SVG, doing so with a clue, for example fixed poit coordinates allows a decent compression over an easy zoom. How good is the SVG support on mobile devices? What about devices without decent SVG support? Do you want to have two rendering pipelines, one SVG for higher pixel ratios and one PNG for less capable devices/browsers? rj ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
[OSM-dev] Retina tiles - best way to support them?
Hi, I have had some people asking whether I could supply them with Retina map tiles. Retina is an Apple brand name for higher resolution displays, and these users tend to mean tiles with twice the resolution. I wonder if anyone has done this already. I can think of a number of possible angles to attack this: 1. Double all font sizes, line widths, etc. in the Mapnik style file (recent Mapnik versions also have a built-in scaling option that achieves about the same) and adapt all scale denominators accordingly. This would mean that meta tile size, tile size, and everything else would remain unchanged but you'd be shifting everything by one zoom level - what was on one z16 tile before is now on four z17 tiles. The Retina user would see less detail on the same zoom level and therefore would have to go down to z19 to see what is currently shown on 18. Also, font nastiness along the metatile edges would increase; the amount of font nastiness depends on the ratio of tile size to font size, so doubling font sizes and keeping metatile sizes will increase label clipping and other strange things. (Simply increasing the buffer doesn't help.) 2. Modify style as per 1., but also double the size of meta tiles to 4096x4096. Cut 16x16 normal tiles out of one meta tile, rather than 8x8. This avoids the increase in font nastiness but requires internal processes to adapt to larger metatiles. The zoom level shift problem is the same as in 1. 3. Modify style as per 1., double size of meta tiles to 4096x4096, and double size of tiles to 512x512. This avoids the increase in font nastiness *and* it has the nice effect that one Retina tile at a certain zoom level shows exactly the same content as a normal tile, just on 512x512 instead of 256x256 and therefore at twice the resolution. It would, however, require clients (OpenLayers et al.) to work with the larger tile size. Your thoughts on these options - are there more than these three, perhaps? - would be most welcome. (Tiles for printing is a very similar issue - print users tend to want quad-resolution tiles, and again you have the options of shifting the zoom level by 2 or making 1024x1024 tiles.) Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09 E008°23'33 ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
Hi, On 26.06.2012 23:05, Frederik Ramm wrote: 3. Modify style as per 1., double size of meta tiles to 4096x4096, and double size of tiles to 512x512. This avoids the increase in font nastiness *and* it has the nice effect that one Retina tile at a certain zoom level shows exactly the same content as a normal tile, just on 512x512 instead of 256x256 and therefore at twice the resolution. It would, however, require clients (OpenLayers et al.) to work with the larger tile size. I just tried this out and found that, on a standard non-mobile Firefox browser, OpenLayers displays the new 512x512 tile just fine, it scales it to 256x256 in the browser. I can then use the browser's zoom function to blow up the OpenLayers display and while everything becomes jaggy when I do this with normal tiles, the map still looks nice when using the double resolution tiles. Does this mean that it would be an acceptable viewing experience for mobile users as well? mod_tile does not require modifications to work with 512x512 tiles; Tirex requires a couple. Also, I'm running this on the standard OSM style and Mapnik 2.0 using the AGG renderer's scale factor parameter and it doesn't scale shields or bitmap icons; I'll see if that's any better with 2.1 - else I'll have to do the old style take xml and double all the sizes route. Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09 E008°23'33 ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Retina tiles - best way to support them?
From: Frederik Ramm [mailto:frede...@remote.org] Subject: [OSM-dev] Retina tiles - best way to support them? Hi, I have had some people asking whether I could supply them with Retina map tiles. Retina is an Apple brand name for higher resolution displays, and these users tend to mean tiles with twice the resolution. I wonder if anyone has done this already. I can think of a number of possible angles to attack this: 1. Double all font sizes, line widths, etc. in the Mapnik style file (recent Mapnik versions also have a built-in scaling option that achieves about the same) and adapt all scale denominators accordingly. I did some work on this for print where I wanted to print 1200 DPI maps. I found that with one exception, everything just worked if I created a mapnik.Image of the higher resolution and used an appropriate scale factor. https://github.com/pnorman/mapbook/blob/master/mapbook.py#L201 is the relevant section of the code. Unfortunately I haven't had time to work on it lately. The one exception to it just working is png POI graphics. These appear at a reduced scale with mapnik's AGG renderer and at the same scale but blocky with the mapnik cairo-based PDF renderer. This is an inherent limitation of bitmapped graphics - it either looks tiny or it looks bad. Fonts and line widths worked perfectly. What I would suggest is a version of osm.xml which uses SVG icons instead of PNG icons, allowing for use at any resolution. Some other points you'll find at high resolution - mapnik takes significantly more CPU time to render at high resolutions - The same style that works at ~100 DPI on a normal screen doesn't work at 1200 DPI printed, aside from any technical considerations. - The difference in appearance you get with each doubling of the resolution decreases as you increase resolution so you may not want to go to the max resolution of the device you have if it is 300 DPI - DPI images are large and it takes planning to deal with them Of the three options you listed, I find 3 the best - it keeps a given z/x/y tile representing the same area. ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
