[OSM-talk] Contour lines
Hi all, Is there a WMS layer or other data source for contour lines? I am improving the outline of the water in a reservoir. I have checked Yahoo! aerials to see the nominal area of the reservoir and I have chosen a particular contour line on OSM Cycle Map to trace along with Potlatch. This will give a pleasing representation of the area covered by the water. Unfortunately, the reservoir is already partially rendered on OSM Cycle Map so it, and other features, obscure some of the contour lines. Would it be useful to have a 'topolines only' map? It wouldn't have to have features on it (as it can be switched in and out in Potlatch and JOSM), and it doesn't have to be rendered very often. In this case I am happy with using the OSM Cycle Map as a background layer for tracing, especially as the new water shape is generally bigger than the old shape. If the new shape was smaller, or badly drawn, or in the wrong place then I would not be able to see the contours underneath it on the OSM Cycle Map. Comments please (esp. easier/better ideas), Thanks, Andrew ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On 13 April 2010 01:26, Andrew Errington a.erring...@lancaster.ac.ukwrote: I have checked Yahoo! aerials to see the nominal area of the reservoir and I have chosen a particular contour line on OSM Cycle Map to trace along with Potlatch. This will give a pleasing representation of the area covered by the water. Hey, hold it right there. What makes you think the Yahoo! imagery and/or the contour lines shown on the Cycle Map(these contours are from SRTM data, not OSM) are more up to date or more accurate/precise than the existing water body drawn in OSM? Also, posting a map url or link to the object of the reservoir in question could be helpful. -- Gregory o...@livingwithdragons.com http://www.livingwithdragons.com ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On Tue, 13 Apr 2010, Gregory wrote: What makes you think the Yahoo! imagery and/or the contour lines shown on the Cycle Map(these contours are from SRTM data, not OSM) are more up to date or more accurate/precise than the existing water body drawn in OSM? Indeed. Also, ISTR the cycle map fakes up realistic looking contours for void-filling doesn't it? I don't think the SRTM contours are accurate enough to use for tracing bodies of water - you need to walk the perimeter with a GPS or use aeriel photos. SRTM data _may_ be useful for guestimating flowing water courses that can't be otherwise surveyed, but for this I think you'd really want to be computing stuff off the raw DEM rather than manually adding features using the (already quite heavilly processed) contour lines. -- - Steve xmpp:st...@nexusuk.org sip:st...@nexusuk.org http://www.nexusuk.org/ Servatis a periculum, servatis a maleficum - Whisper, Evanescence ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On Tue, Apr 13, 2010 at 10:59 AM, Steve Hill st...@nexusuk.org wrote: I don't think the SRTM contours are accurate enough to use for tracing bodies of water - you need to walk the perimeter with a GPS or use aeriel photos. They aren't. There's also another source called SRTM Water Body dataset ( http://www.kcl.ac.uk/schools/sspp/geography/research/emm/geodata/landandwater.html) but they both are fairly inaccurate. Regards, Igor ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
Am 13.04.2010 10:48, Gregory: On 13 April 2010 01:26, Andrew Errington a.erring...@lancaster.ac.uk mailto:a.erring...@lancaster.ac.uk wrote: I have checked Yahoo! aerials to see the nominal area of the reservoir and I have chosen a particular contour line on OSM Cycle Map to trace along with Potlatch. This will give a pleasing representation of the area covered by the water. Hey, hold it right there. What makes you think the Yahoo! imagery and/or the contour lines shown on the Cycle Map(these contours are from SRTM data, not OSM) are more up to date or more accurate/precise than the existing water body drawn in OSM? These thoughts set aside here's a SRTM contour tiles link: [1] I suggest reading about SRTM as well [2] so that you can assess this data source. For example the 90m resolution outside the USA. Claudius [1] http://www.christeck.de/wp/2010/01/09/srtm-tiles-available-online/ [2] http://en.wikipedia.org/wiki/SRTM ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On Tue, 13 Apr 2010, Steve Hill wrote: SRTM data may be useful for guestimating flowing water courses that can't be otherwise surveyed, I can show you SRTM data that shows elevations in the flat plain at all the watercourses - it picks off the the tree tops which grown in the river bed and it happens on the Hay plain, one of the very large very very flat areas on Earth ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On 13 April 2010 01:59, Steve Hill st...@nexusuk.org wrote: ...for tracing bodies of water - you need to walk the perimeter with a GPS... I've always wanted to fix up a pole about 6-10ft with a secure GPS mount on one end, and possibly a harness or neck strap to carry the other end on me. Then walk along the side of a river/lake at a safe distance with my GPS hovered above the line where the water meets the bank. A similar idea entered my mind where I would have a kick stand on my bicycle and a broom pole sticking up from the bike. I would stand the bike some distance away from the corner of a building and note the GPS location of the bike, record another location where my line of sight of the building corner is obstructed by the broom pole from the bike. I repeat for a few more line bike and sight positions. So at home I have pairs of points (bike and view/sight) I draw lines between them and extend each line beyond it's point (keeping the angles). Where the lines cross is the location of the building corner. I also repeated all this for the other building corners (let's hope it was a simple rectangle) and I have produced a good outline/positioning of the building where perhaps I could not get up next to it (or it's height created an urban canyon for my GPS). Now a days I'm just thinking about possible data imports and when Yahoo! will fly over that countryside industrial park surrounded with ponds. How boring. -- Gregory o...@livingwithdragons.com http://www.livingwithdragons.com ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On Tue, 13 Apr 2010, Gregory wrote: I've always wanted to fix up a pole about 6-10ft with a secure GPS mount on one end, and possibly a harness or neck strap to carry the other end on me. Then walk along the side of a river/lake at a safe distance with my GPS hovered above the line where the water meets the bank. You could just walk 3m from the water all the time and then when you trace the track just offset the trace by 3m. :) -- - Steve xmpp:st...@nexusuk.org sip:st...@nexusuk.org http://www.nexusuk.org/ Servatis a periculum, servatis a maleficum - Whisper, Evanescence ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On Tue, Apr 13, 2010 at 9:59 AM, Steve Hill st...@nexusuk.org wrote: On Tue, 13 Apr 2010, Gregory wrote: What makes you think the Yahoo! imagery and/or the contour lines shown on the Cycle Map(these contours are from SRTM data, not OSM) are more up to date or more accurate/precise than the existing water body drawn in OSM? Indeed. Also, ISTR the cycle map fakes up realistic looking contours for void-filling doesn't it? Indeed. Moreover, if you were to peel away the lakes that are in there, you'd find many of them have contour lines running under them, since the SRTM data is much less accurate than OSM data. It's really just a bodge to make things look pretty (and to help you see which way is uphill/downhill) rather than a serious datasource. It'll be even worse in a few weeks when I start smoothing out the contours, making them even more fake then they are already. In saying that, if the existing lake is especially crappy (e.g. a rectangle) and large (over 1km) then I could see how you can improve the shape with the aid of some contours. Cheers, Andy ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On Tue, 13 Apr 2010 17:59:47 Steve Hill wrote: On Tue, 13 Apr 2010, Gregory wrote: What makes you think the Yahoo! imagery and/or the contour lines shown on the Cycle Map(these contours are from SRTM data, not OSM) are more up to date or more accurate/precise than the existing water body drawn in OSM? Indeed. Also, ISTR the cycle map fakes up realistic looking contours for void-filling doesn't it? I don't think the SRTM contours are accurate enough to use for tracing bodies of water - you need to walk the perimeter with a GPS or use aeriel photos. SRTM data _may_ be useful for guestimating flowing water courses that can't be otherwise surveyed, but for this I think you'd really want to be computing stuff off the raw DEM rather than manually adding features using the (already quite heavilly processed) contour lines. My goodness! Care to estimate the accuracy of the Yahoo! aerials? In this region they are a bit fuzzy, and not very well aligned with WGS84. My GPS accuracy (reported by the device itself) is at best 4m, but in mountainous regions or in cities it is 5m or 6m at best, often worse. How accurate is my mouse when I click on a pixel? Visually I am interpolating the (inaccurate) GPS trace to get a smooth, pleasing curve or shape. Although we strive for accuracy you have to remember we are not surveying, we are making a map; there is a difference. In the case of the reservoir, the contour lines line up remarkably well with other map features (which were recorded independently of the contours, but plotted together to make the OSM cycle map). Rivers follow gullys, roads snake appropriately over dense contour lines, etc., so I see no reason not to use them. Furthermore, the reservoir level changes throughout the year, depending on the weather. Yahoo! may have snapped a picture of the average level, or a minimum. If I go there with my GPS I cannot get to the water's edge- it's too dangerous, so I have to estimate where the waterline would be based on my (inaccurate) GPS and (inaccurate) memory and notes. The previous version of the reservoir is jagged and rough- a few points clicked around the perimeter. The body of water is about 16km long. I wish to make the reservoir outline better. I cannot get an aerial of the reservoir when full. I cannot walk around the water's edge. I don't have an RC model speedboat with my GPS on it (yes, I thought about it) so I will use the next best thing at my disposal. SRTM contours. The next guy that comes along will improve it, as I have done, and as we all do. Having said that, I have just compared my changes with Google aerials, Google Maps, and another two mapping providers. They are all different, but mine is a little high, so I am going to choose the next lowest contour. Best wishes, Andrew ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On Tue, 2010-04-13 at 11:14 +0200, Claudius wrote: Am 13.04.2010 10:48, Gregory: On 13 April 2010 01:26, Andrew Errington a.erring...@lancaster.ac.uk mailto:a.erring...@lancaster.ac.uk wrote: I have checked Yahoo! aerials to see the nominal area of the reservoir and I have chosen a particular contour line on OSM Cycle Map to trace along with Potlatch. This will give a pleasing representation of the area covered by the water. Hey, hold it right there. What makes you think the Yahoo! imagery and/or the contour lines shown on the Cycle Map(these contours are from SRTM data, not OSM) are more up to date or more accurate/precise than the existing water body drawn in OSM? These thoughts set aside here's a SRTM contour tiles link: [1] I suggest reading about SRTM as well [2] so that you can assess this data source. For example the 90m resolution outside the USA. If it's the UK you're interested in then you should look at the newly released Land-Form PANORAMA data from the OS[3]. I've played with viewing it in QGIS and it looks fantastic. Some of the other data released might also be of interest for water body mapping. Keith. [3] https://www.ordnancesurvey.co.uk/opendatadownload/products.html ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On Tue, 13 Apr 2010, Andrew Errington wrote: My GPS accuracy (reported by the device itself) is at best 4m, but in mountainous regions or in cities it is 5m or 6m at best, often worse. How accurate is my mouse when I click on a pixel? Visually I am interpolating the (inaccurate) GPS trace to get a smooth, pleasing curve or shape. Although we strive for accuracy you have to remember we are not surveying, we are making a map; there is a difference. Well yes, but the SRTM DEM has 90 metre pixels. If you're using the data that has been processed into contour lines then that is going to be a whole lot worse even before you start taking into account stuff like void filling and contour smoothing. Like it or not, tracing SRTM contours is probably going to leave you a couple of orders of magnitude away from GPS accuracy. -- - Steve xmpp:st...@nexusuk.org sip:st...@nexusuk.org http://www.nexusuk.org/ Servatis a periculum, servatis a maleficum - Whisper, Evanescence ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On 13 April 2010 23:01, Andrew Errington a.erring...@lancaster.ac.uk wrote: I'm still tempted to get an RC boat and tape the GPS on top. Some people are playing with RC planes and GPS + cameras... ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines
On 13/04/2010 11:20, Andrew Errington wrote: Having said that, I have just compared my changes with Google aerials, Google Maps, and another two mapping providers. They are all different, but mine is a little high, so I am going to choose the next lowest contour. If the place is in the UK, the recently released OS OpenData includes some resources you should look at. Both contour data and lakes are included in http://wiki.openstreetmap.org/wiki/Ordnance_Survey_Opendata#Land-Form_PANORAMA apparently. There is also VectorMap District which is to be released next month. -- Steve ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines from SRTM-Data in OSM format
CE, I am interested to get Phiilippine contours in img http://openstreetmap.org/?lat=12.24lon=122.07zoom=6layers=B000FTF cheers, maning On Sat, Nov 15, 2008 at 8:00 AM, Christoph Eckert [EMAIL PROTECTED] wrote: Hi, I have used srtm2osm (all credits to Igor Brejc) to convert srtm data into OSM contour lines. All tiles are zippes in zip format and the complete world consumes 61G of disk space. See some example at [1]. I have some questions so far: * I have no clue if there's some interest in the data, but if so, what would be the best method to distribute it? I thought about Bittorrent, but I have no clue if it is sufficient if there only are a couple of downloaders. * OSM2Navit just crashes when I try to convert the tiles for Navit. So if someone knows a little bit more about C than me... ;-) * One further usage of the data was to convert it as Garmin tiles, using a transparent background. This way, the data could be used in conjunction with openstreetmap, well, maps :) . I do not use such maps on Garmin, but if someone fiddles out how to do it best, we surely can run a script again. * If someone needs an individual tile, do not hesitate to drop me a line :) . Cheers, ce [1] http://www.christeck.de/wp/?p=114 ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk -- |-|--| | __.-._ |Ohhh. Great warrior. Wars not make one great. -Yoda | | '-._7' |Freedom is still the most radical idea of all -N.Branden| | /'.-c |Linux registered user #402901, http://counter.li.org/ | | | /T |http://esambale.wikispaces.com/ | | _)_/L I http://epsg4253.wordpress.com/ | |-|--| ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines from SRTM-Data in OSM format
I believe srtm2osm uses void filled data that is copyrighted. So is you do distribute the results make sure that you specify it's only for academic research. IANAL. I used srtm2osm to make an OSM file of over 1 GB and played around with it in gosmore. Distributing gosmore files that include srtm contours will be pretty cool especially for hiking. But making a setup that uses the PD data and does not exceed the 420MB limit on WinCE will take some effort. Regards, Nic On Sat, Nov 15, 2008 at 2:00 AM, Christoph Eckert [EMAIL PROTECTED] wrote: Hi, I have used srtm2osm (all credits to Igor Brejc) to convert srtm data into OSM contour lines. All tiles are zippes in zip format and the complete world consumes 61G of disk space. See some example at [1]. I have some questions so far: * I have no clue if there's some interest in the data, but if so, what would be the best method to distribute it? I thought about Bittorrent, but I have no clue if it is sufficient if there only are a couple of downloaders. * OSM2Navit just crashes when I try to convert the tiles for Navit. So if someone knows a little bit more about C than me... ;-) * One further usage of the data was to convert it as Garmin tiles, using a transparent background. This way, the data could be used in conjunction with openstreetmap, well, maps :) . I do not use such maps on Garmin, but if someone fiddles out how to do it best, we surely can run a script again. * If someone needs an individual tile, do not hesitate to drop me a line :) . Cheers, ce [1] http://www.christeck.de/wp/?p=114 ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines from SRTM-Data in OSM format
Nic Roets wrote: I believe srtm2osm uses void filled data that is copyrighted. So is you do distribute the results make sure that you specify it's only for academic research. IANAL. No, it uses original SRTM data downloaded directly from NASA's FTP server. Regards, Igor -- http://igorbrejc.net ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines from SRTM-Data in OSM format
Hi, I believe srtm2osm uses void filled data that is copyrighted. So is you do distribute the results make sure that you specify it's only for academic research. IANAL. No, it uses original SRTM data downloaded directly from NASA's FTP server. I've been on the SRTM pages a couple of minutes before, and am still unsure about the license stuff. Before I distribute the data, I'd really like to know if it is legal. Any hint would be much appreciated. Best regards, ce ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines from SRTM-Data in OSM format
Christoph Eckert wrote: Hi, I believe srtm2osm uses void filled data that is copyrighted. So is you do distribute the results make sure that you specify it's only for academic research. IANAL. No, it uses original SRTM data downloaded directly from NASA's FTP server. I've been on the SRTM pages a couple of minutes before, and am still unsure about the license stuff. Before I distribute the data, I'd really like to know if it is legal. Any hint would be much appreciated. Best regards, ce Well, first of all, CycleMap uses the same SRTM data (as far as I know), so if the license is an issue, this applies to CycleMap too. I haven't been able to find any info directly describing the license of SRTM, but, as far as I know, all NASA's products (images, data) are public domain. And since people who generated SRTM void-filled data license it under their own terms (and not NASA's), I guess this means that the original data has a very permissive license. So we should be in the clear ;) Igor -- http://igorbrejc.net ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] Contour lines from SRTM-Data in OSM format
On Sat, Nov 15, 2008 at 10:10 AM, Igor Brejc [EMAIL PROTECTED] wrote: Well, first of all, CycleMap uses the same SRTM data (as far as I know), so if the license is an issue, this applies to CycleMap too. I haven't been able to find any info directly describing the license of SRTM, but, as far as I know, all NASA's products (images, data) are public domain. And since people who generated SRTM void-filled data license it under their own terms (and not NASA's), I guess this means that the original data has a very permissive license. So we should be in the clear ;) the license for CGIAR's void-filled dataset is here: http://srtm.csi.cgiar.org/SELECTION/SRT_disclaimer.htm it looks like using the dataset for deriving contours for non-commercial use is OK as long as the contours (and tiles based on them) are attributed to CGIAR. cheers, matt ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
[OSM-talk] Contour lines from SRTM-Data in OSM format
Hi, I have used srtm2osm (all credits to Igor Brejc) to convert srtm data into OSM contour lines. All tiles are zippes in zip format and the complete world consumes 61G of disk space. See some example at [1]. I have some questions so far: * I have no clue if there's some interest in the data, but if so, what would be the best method to distribute it? I thought about Bittorrent, but I have no clue if it is sufficient if there only are a couple of downloaders. * OSM2Navit just crashes when I try to convert the tiles for Navit. So if someone knows a little bit more about C than me... ;-) * One further usage of the data was to convert it as Garmin tiles, using a transparent background. This way, the data could be used in conjunction with openstreetmap, well, maps :) . I do not use such maps on Garmin, but if someone fiddles out how to do it best, we surely can run a script again. * If someone needs an individual tile, do not hesitate to drop me a line :) . Cheers, ce [1] http://www.christeck.de/wp/?p=114 ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
