Re: [Qgis-user] Fwd: New and inexperienced--how to make NASA SRTM work properly?
Hi You could also try OpenEV for 3d visualisation Regards Tim 2007/2/10, Amanda Wintcher [EMAIL PROTECTED]: Brent Wood wrote: QGIS (AFAIK) does not support 3D displays of terrain models. It can display vector (point/line/polygon) and georeferenced raster (terrain models, imagery) in 2D (from above) only- basically a plan view. Whoops! I guess I missed that very simple piece of information! Sorry about that. To use SRTM data with QGIS, I believe you'll need to generate georeferenced images from the SRTM terrain model, or download such imagery. GRASS GMT can generate such imagery from the SRTM model. QGIS does not have the analytical capabilities to do this (yet). As said elsewhere on the list, I don't really need to be able to see the data as 3D (except that it will impress my advisors), and I don't plan to try and print anything other than flat images in the final product. I presume that if I have the information in the file, generated using one of the methods above, that I can still use the elevation data in calculations of things like visibility or slope via qGIS? Or am I really better off using GRASS by itself? Thank you all very much for your help and patience. Amanda ___ Qgis-user mailing list Qgis-user@lists.qgis.org http://lists.qgis.org/cgi-bin/mailman/listinfo/qgis-user -- -- Tim Sutton Visit http://qgis.org for a great Open Source GIS Home Page: http://linfiniti.com Skype: timlinux MSN: [EMAIL PROTECTED] Yahoo: [EMAIL PROTECTED] Jabber: timlinux Irc: timlinux on #qgis at freenode.net ___ Qgis-user mailing list Qgis-user@lists.qgis.org http://lists.qgis.org/cgi-bin/mailman/listinfo/qgis-user
Re: [Qgis-user] Fwd: New and inexperienced--how to make NASA SRTM work properly?
Brent Wood wrote: QGIS (AFAIK) does not support 3D displays of terrain models. It can display vector (point/line/polygon) and georeferenced raster (terrain models, imagery) in 2D (from above) only- basically a plan view. Whoops! I guess I missed that very simple piece of information! Sorry about that. To use SRTM data with QGIS, I believe you'll need to generate georeferenced images from the SRTM terrain model, or download such imagery. GRASS GMT can generate such imagery from the SRTM model. QGIS does not have the analytical capabilities to do this (yet). As said elsewhere on the list, I don't really need to be able to see the data as 3D (except that it will impress my advisors), and I don't plan to try and print anything other than flat images in the final product. I presume that if I have the information in the file, generated using one of the methods above, that I can still use the elevation data in calculations of things like visibility or slope via qGIS? Or am I really better off using GRASS by itself? Thank you all very much for your help and patience. Amanda ___ Qgis-user mailing list Qgis-user@lists.qgis.org http://lists.qgis.org/cgi-bin/mailman/listinfo/qgis-user
[Qgis-user] Fwd: New and inexperienced--how to make NASA SRTM work properly?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Begin forwarded message: From: Amanda Wintcher [EMAIL PROTECTED] Date: February 9, 2007 6:19:36 AM AKST To: [EMAIL PROTECTED] Subject: New and inexperienced--how to make NASA SRTM work properly? Reply-To: [EMAIL PROTECTED] Apologies if this is too basic (or long) for this list. I have downloaded some SRTM tiles (version 2 from ftp://e0srp01u.ecs.nasa.gov/srtm/), and I am particularly interested in N038W002 (Murcia, southeastern Spain). I have some problems that I don't know how to solve, and the User Guide doesn't give enough detail to figure them out. How do I make the SRTM data appear as 3-D digital elevation models? I had some help from another person who was able to make it work with an older version of ArcGIS, but I don't know how to reproduce it with qGIS. This is what I have tried: Opened the .hgt file in 3 DEM, making sure to select the NASA SRTM option. Change projection to UTM has four ellipsoid options: WG84, WGS72, NAD83, and NAD27. I have tried all four in order to see what UTM coordinates I get for the corners of the tile. To check myself, I then opened up the GEOTRANS 2.3 program in order to convert the lat/lon coordinates to UTMs. However, I don't know which ellipsoid to pick for this part--what is the appropriate choice for the SRTM data? None of the options gives the same UTM coordinate for the southwest corner of the tile in both programs. I saved the SRTM file as a GeoTiff DEM in any case, using the WG84 datum, as I have a set of shape files with an outline of the region and topo lines that someone else has given me and that is the system they use according to the metadata in qGIS. I then changed the projection to the following: QGIS SRSID: 1248 PostGIS SRID: 23030 +proj=utm +zone=30 +ellps=intl +units=m +no_defs which is described as ED50 UTM Zone 30N, which should be what I want so far as I can tell, based on the info on the paper maps I am using to navigate on the ground. So far, I have managed to get all of the layers in the same place and they look to be in the right spot. But how do I now make the 3-D information visible beyond a greyscale background? What is this kind of operation actually called? I have no experience in GIS but I am trying to use qGIS for my PhD project. I have a set of archaeological sites and I want to look at their geographic context (e.g. landforms, visibility, etc.) in an attempt to assess how different kinds of sites are related to each other. Thanks for any help. A pointer to a more comprehensive manual (other than the user guide), preferably something that I can download or otherwise consult offline, would be great, too. By the way, I am using qGIS 0.8.0 (Titan). According to the about page, it has PostgreSQL support and is compiled/running against Qt 4.2.2, if that means anything. It's on Windows XP, and I have previously installed the experimental native windows GRASS version 6.3.cvs. That seems to work okay as the GRASS tools in qGIS seem to be fine. I don't know anything about coding or writing scripts, but I'm not afraid to learn how! Amanda - -_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_- Gary Sherman Micro Resources: http://mrcc.com *Geospatial Hosting *Web Site Hosting We work virtually everywhere - -_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_- -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.1 (Darwin) iD8DBQFFzJGZ1zKuzV6goTgRAuiNAJ4nJoJJyuTe08f2ZXAbzvnStimBxQCeO+XA uTSq3MfBJAHSfWt0rPQ3WDk= =QHJt -END PGP SIGNATURE- ___ Qgis-user mailing list Qgis-user@lists.qgis.org http://lists.qgis.org/cgi-bin/mailman/listinfo/qgis-user
Re: [Qgis-user] Fwd: New and inexperienced--how to make NASA SRTM work properly?
Apologies if this is too basic (or long) for this list. I have downloaded some SRTM tiles (version 2 from ftp://e0srp01u.ecs.nasa.gov/srtm/), and I am particularly interested in N038W002 (Murcia, southeastern Spain). I have some problems that I don't know how to solve, and the User Guide doesn't give enough detail to figure them out. QGIS (AFAIK) does not support 3D displays of terrain models. It can display vector (point/line/polygon) and georeferenced raster (terrain models, imagery) in 2D (from above) only- basically a plan view. To use SRTM data with QGIS, I believe you'll need to generate georeferenced images from the SRTM terrain model, or download such imagery. GRASS GMT can generate such imagery from the SRTM model. QGIS does not have the analytical capabilities to do this (yet). For Open Source GIS type tools to display 3D data, in 3D, I've used GRASS (NVIZ) and OpenDX. Note that GMT can render a 3D view of a terrain model, but just generates the single image, it does not provide the ability to view rotate the model in a virtual 3D space on screen, but this generally is better for publication quality cartography than the others which provide better on screen vizualisation. A package like VIZ5D may also do what you want. see these for examples/info: http://www.ssec.wisc.edu/~billh/vis5d.html http://grass.itc.it/grass60/screenshots/viz.php http://www.opendx.org/highlights.php?highlight=inaction%2Fgis%2FSubmit=Go HTH, Brent Wood ___ Qgis-user mailing list Qgis-user@lists.qgis.org http://lists.qgis.org/cgi-bin/mailman/listinfo/qgis-user
