Hi Viktor > 1) Is there a possibility in QGIS to use *polyline *layer as a source of > interpolation (TIN creation)? If no, is it possible to add this > functionality in the future?
Yes. Additionally, you may set in the 'type' combo if the plugin should just consider the vertices or treat the lines as structure lines / break lines > 2) Is there a possibility in QGIS to *limit* interpolation borders by > another polygonal non-heights layer (such as Arc/Info 'soft clip')? At the moment not > 3) What is a dimension of cell coordinates? Are they use the same units as > projected point layer units? They are the same as the (unprojected) layer units. The interpolation plugin just considers the layer and not the projection of the canvas map. > 4) Which format QGIS saves TIN in? ASCII grid (text format). I know this is not optimal for large datasets. Patches are welcome to extend the hardcoded grid file writing (qgsgridfilewriter) with a solution that uses available GDAL drivers for grid file writing. Regards, Marco Am Dienstag, 26. Januar 2010 12.10:40 schrieb Viktor Kolesnyk: > Hi! > > I was using Arc/Info under Windows XP and now I migrated to Linux Gentoo > and want to migrate to QGIS. > > One of the tasks I used Arc/Info for is *height (elevation) matrix > creation*. I have polyline and point layers as sources. The former layer > is more accurate. > In Arc/Info I did it in two steps: > 1) TIN creation from polyline layer. I also use a territory polygonal layer > to limit interpolation borders (so called '*soft clip*'). > 2) Convert TIN to Raster (in Arc/Info Binary Grid, *.adf) with 100*100 > meters cell size. > As a result I had 547 Mb raster layer *.adf file and some smaller > informative *.adf files. > > I read QGIS 1.3.0 user guide and Marco's "Terrain Modelling with Triangle > Based Free-Form Surfaces" thesis and > as I understand there is only possibility to use point layers to create TIN > in QGIS?! > So, I tried this functionality in QGIS 1.4.0 under Gentoo Linux. > I projected my point layer from Geographical Coordinate System to Projected > CS (WGS84). > Then set it as the source in Interpolation Plugin window and chose 100*100 > (as I understand in meters) cell size of output layer. > I don't know which format QGIS saves TIN in and there is no filters of file > extensions in "Save interpolated layer as..." window. > So, I simply chose "tin.adf". As a result of interpolation I have 2,5 Gb > file, that seems to be less accurately than my 547 Mb Arc/Info Binary grid > one. > > Some questions: > 1) Is there a possibility in QGIS to use *polyline *layer as a source of > interpolation (TIN creation)? If no, is it possible to add this > functionality in the future? > 2) Is there a possibility in QGIS to *limit* interpolation borders by > another polygonal non-heights layer (such as Arc/Info 'soft clip')? > 3) What is a dimension of cell coordinates? Are they use the same units as > projected point layer units? > 4) Which format QGIS saves TIN in? > -- Dr. Marco Hugentobler HUGIS - GIS programming and consulting Webereistrasse 66 CH-8134 Adliswil ma...@hugis.net http://homepage.hispeed.ch/hugis Technical Advisor QGIS Project Steering Committee _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user