Source: https://www.scribd.com/document/82903191/3D-Visual-is-at-Ion-and-Analysis-of-Archaeological-Data-Analysis-Using-Open-Source-GIS
Timestamp: 2019-04-22 08:41:40+00:00

Document:
Documentation.thehumanjourney. Paraview 5. Vector Limitations 6.. Point extraction from shapefiles for 3D point production 3.gvsig.net/462/ Software sources and downloads: Qqis: http://qgis. Useful information / websites Manuals and documentation produced by Oxford Archaeology North: Hodgkinson. Import into GRASS and export of VTK vector data 2. Oxford Archaeology North.paraview. (Unpublished): http://library.CONTENTS Page 3 4 4 5 6 8 8 9 9 9 10 12 13 14 14 INTRODUCTION RASTER DATA VISUALISATION AND PRODUCTION 1. Clipping/Masking of raster files 3. Export of VTK raster (volume) data VECTOR DATA 1. Anna (2010) Archaeological maps from qGIS and Inkscape: A brief guide. (Unpublished): http://library. Import of raster files: 2.eu/ Paraview: http://www.pgadmin. Anna (2010) Open Source Survey & GIS Manual.net/software/gvsigoade gvSIG website: http://www.gov/codes/visit/ pgAdmin: http://www.llnl. (Unpublished): http://library.org/ 2 . Documentation.thehumanjourney.net/366/ Hodgkinson. Christina and Campbell. Anna (2011) Using the Helmert (two-point) transformation in Quantum GIS.thehumanjourney.org/ gvSIG OA Digital Edition 2010: http://oadigital. Oxford Archaeological Unit Ltd. 3D region settings 6. Production of raster volumes 5.org/ VisIt: https://wci.fbk. Dana and Hodgkinson. Documentation.net/367/ Robinson. Oxford Archaeology North. Interpolation – Rasterisation 4. Visualisation 4.org/ Inkscape: http://inkscape.org/web/ GRASS GIS: http://grass.
In addition to these methodologies. this guide contains sections on the problems encountered whilst using the open source geospatial software. and points towards alternative steps undertaken. By no means does this document claim to be complete. Each step described contains information on the software used.INTRODUCTION This document has been produced by Oxford Archaeology North as result of some research undertaken into using exclusively open source geospatial software. Whilst QGIS appears to be the most user-friendly. it is sometimes limited in its functionality. This manual assumes a basic knowledge of the principles of GRASS GIS and the competency to set up a GRASS mapset and location. The visualisation tool used the most was Paraview. it is very much a working document. ALL regular GRASS commands can be executed via the GRASS shell in the QGIS GRASS Plugin (in the “Modules Tree” tab of the GRASS toolbox). some of the options given when executing a command vary between all graphical user interfaces (GUI). 3 . further information can be found in the GRASS documentation on the project website. mainly GUI-based version. which is sometimes still very much under development. Should this knowledge not be present. intended as a “final version”. both the standalone. Please Note: All GRASS software used is to 99% interchangeable. as the commands fulfil the same functions in each piece of software. The author has little familiarity with using a purely command-line based GRASS. and has therefore relied on the three different GUIs. which will hopefully be useful to the reader as well. or indeed. Should only the “raw” command be entered into the shell. The methodologies captured include guides for the visualisation of 3D vector and raster data. the wxPython GUI will open. some information on the analysis of the same. The main software used in this methodology is GRASS GIS. However. but the GRASS plugin in Quantum GIS (QGIS) or that in SEXTANTE (gvSIG OADE) were also frequently used. However.
qgis) • Problems encountered: Location boundaries did not match.4 wxPython GUI) • Open the mapset • Import “loaded raster layers” one by one into GRASS using the QGIS plugin (r. Import of raster files: • GRASS (QGIS GRASS Plugin.RASTER DATA VISUALISATION AND PRODUCTION 1.4 on Ubuntu and GRASS 6.region): and then select the raster / vector map the extents of which to set the region to. The raster will now display via NVIZ: 4 . GRASS 6. therefore raster would not display in 3D NVIS: • The solution is to set the region boundary to match the extent of the loaded raster after import: GRASS wxPython or GRASS shell through QGIS: Config – Region – Set Region (g.gdal.in.
Clipping/Masking of raster files • QGIS GRASS Plugin: • Import the vector file / layer you wish to clip the raster file to into GRASS using v.ogr – in the “options” tab tick “extend location extents based on new dataset”! • • Convert the vector boundary layer into a raster file using v.mask and select “boundary_rast @PERMANENT” as the raster to use for MASK: The clipped raster will also display in NVIZ. call it something like “boundary_rast” Then use r.rast in order to create a MASK for clipping.2. as it has not actually been cropped.to. but simply masked and the file remains the same! 5 .in.
: The result will have to be masked (see above). Interpolation – Rasterisation: • GRASS 6.surf.to.4 wxPython GUI/QGIS GRASS Plugin: • v.idw (Inverse Distance Weighting) – select a previously imported 3D points layer as input and select layer/layer number = 0 (in this case the z-coordinate of the 3D points layer is interpolated.Save as a GeoTiff N. unless the current region extents have been set to match : 6 . although this can be used as well) . rather than a z-attribute.“values” and “settings” tabs! • • • use v.3.B.3d to turn a 2D points layer into 3D beforehand Save the resulting raster layer: Highlight the image and right-click: “save as” .
7 . but can be saved to Geotiff format once added to the TOC. ◦ Output files are automatically saved in . extent will be automatically calculated from data. ◦ Display the resulting file in “Pseudocolour” (properties). ◦ Method: IDW or TIN.• • QGIS: Plugins – Interpolation – Interpolation (plugin will have to be installed via the plugins manager): • Select the vector points layer from the dropdown menu.asc format. The images are loaded automatically with WGS84 projection – change this in the “Properties – General” to the appropriate grid. Hit “Add”. Select the attribute containing the elevation information. Cellsize x and y: depends on resolution of vector point data.
3D region settings: • g.fbk.region: Whilst the 2D resolution / region can be set using a 2D raster.nabble.rast3: • Select one or several 2D rasters that are to be turned into a 3D raster • Give the resulting raster a name • Further.vtk files which can then be displayed in open source 3D visualisation software Paraview. detailed documentation on: http://osgeo-org.html • N.html 8 .com/error-message-cache-queueenqueue-position-not-in-queue-td1884896.region.eu/gdp/html_grass64/g. Paraview section): • r.4. detailed documentation on http://grass.B.to. the 3D resolution will have to be refined using res3= • Should the resolution in the Z-axis be different to that of the x-y plain "tbres=" can be used to adjust. Production of raster volumes • GRASS wxPython • GRASS exports 3D raster files as 3D . • -p3 will print all current settings. and slices can be drawn through these (see below.n2.1803224. so they can be checked • Further.: NVIZ will more than likely not display the result (possible bug) 5.
vtk: v. This will only work for numerical data.3d – important to select attribute for height in “Height” tab! Same can be done with v.vtk input=<grass-voxel-map> output=output-file.in.vtk ◦ Further.vtk.vtk: ◦ Ignore the surface creation option ◦ use the -p flag (tick “create grid points” rather than raster vtk data) ◦ In the “optional” tab select the 3D raster ◦ specify the filepath for the resulting .6.connect – make sure to specify table name and key column! ◦ Turn into 3D vector layer: v.out.vtk.vtk file can be loaded and displayed in Paraview 9 .vtk file (remember the file extension) ◦ basic formula for command output: r3. in order to export numeric values with the vtk file: use the "n" flag in v. Import into GRASS and export of VTK vector data • 3D points: ◦ Import into GRASS from shapefile v.html VECTOR DATA 1.osgeo.to.out. textual attributes will be lost ◦ The .out.out.org/gdp/html_grass64/r3. detailed documentation on http://grass.vtk.extrude ◦ Export as .db.out. Export of VTK raster (volume) data • r3.ogr – DO NOT TICK “create 3D output” ◦ Re-establish connection between vector data and attribute data (is frequently lost during import): v.
line” Make sure to set the region to match the layer's extent.2. “type” must be “boundary.10 Edition with GRASS in SEXTANTE: conversion of 3D polygons: load 3D polygon shapefiles in a new gvSIG project view (the 3D shapefile needs to have elevation values within its attribute table) • • GRASS: v. The result of v.type – converts 3D polygons into 3D lines.type: 3D lines 10 . • • • Point extraction from shapefiles for 3D point production gvSIG OA Digital 1.
in gvSIG.to.out. • From GRASS export these points as . select all the "point_label" records and delete them). however. an elevation field should be present! The data should have been duplicated.check the attribute table of the dxf.dxf as a layer to the TOC . This produces a 3D points layer. lines: Ignore polygons and lines.dxf (won't work as shapefile! Attribute data won't be exported!) or from gvSIG do “Layer – Export to – AutoCAD DXF” and save the file (make sure the layer is selected in the TOC).points – extracts points (vertices) from the result layer of v.this will turn the data into 3D and wipe out the "elevation" column!! Save the dxf as a shapefile (highlight layer in TOC and do "layer .type: select only “vertices”. in SEXTANTE the resulting points layer will have to be edited and both the “cat” and the “_cat” columns deleted from the attribute table.• v. this should be 2DPoint! The point layer can now be edited and the duplicates should be deleted (Filter.export to shapefile") .dxf: v. This operation can be run in other GRASS software. add the . work only with points: check the properties of this layer. and in the "Layer" column one should find both point and point_label.this will produce three shapefiles: points. • • Then. The result should be a 2D points shapefile that contains the elevation of each point as an attribute within its table! • • • • 11 . polygons. DO NOT EDIT THE DXF .
select the layer to be added.4: ◦ Load the raster layers into the display window in GRASS – add as many as you wish to display ◦ Hit the NVIZ button at the top of the display window ◦ Should you want to add more layers. follow the steps above for “Displaying several layers in NVIZ on QGIS” • N.3. hit “accept” and “accept” again • Displaying several layers in NVIZ on GRASS 6. Visualisation • GRASS: NVIZ (QGIS GRASS Plugin. wait until the NVIZ window opens ◦ Then: Toolbar: Visualize – Raster surfaces ◦ Hit “New” next to the name of the currently displayed layer (left of the display window) ◦ When the box pops up hit “New map”.4 wxPython GUI) • Displaying one or more 2D or 3D raster layers in NVIZ: • Displaying several layers in NVIZ on QGIS: ◦ The layers to be displayed in NVIZ MUST be active and in the TOC of the current QGIS project.B. GRASS 6.: ◦ It is not possible to group layers ◦ The “z-exaggeration can be altered through a sliding bar ◦ NVIZ creates sections through displaying “cutting planes”: ◦ Visualize – Cutting Plane ◦ NVIZ should allow the display of volumes (but they do not display – possible bug) 12 .4 on Ubuntu and GRASS 6. otherwise they will not be listed in the GRASS toolbox! ◦ Load up one single layer (through the GRASS toolbox).
4. Paraview : • Upload files to Paraview • “Edit . can be turned off • It is difficult to face the section properly – no fixed axes for rotating the objects in 3D: • Add a “colour legend” (view – show colour legend): • Group several layers if necessary: Draw a slice. or run other analyses with several datasets: • 13 .rotation axes etc.view settings” .
but will work in ArcGIS10 ◦ Problems: ◦ r3.net/366/ (Robinson. see http://library. Oxford Archaeology North. Christina and Campbell.eu/gdp/tutorials. 9. Documentation.• File – Save screenshot – set resolution and quality. Useful information / websites http://grass. Dana and Hodgkinson.osgeo.fbk. (Unpublished) for a guide on using Inkscape 8.org/grass62/manuals/html62_user/raster3dintro. Anna (2010) Archaeological maps from qGIS and Inkscape: A brief guide. but will work in ArcGIS10 • Explanation: Both QGIS (including QGIS GRASS plugin) and SEXTANTE (in gvSIG) lack support for 3D vectors in application's internal geometry model.mapcalculator (in GRASS) will not work for the query in neither Paraview nor VisIt • Clipping of 3D TIN shapefiles • This type of 3D QUERY is not possible in GRASS. export as PDF • The PDF can be edited in Inkscape.thehumanjourney. Vector Limitations: • Query of 3D point data by raster surface ◦ This type of 3D QUERY is not possible in GRASS.html 14 .php http://grass.

References: v. 
 v. 
 v.

 v. 
 v. 
 v.