Making use of GIS software

• geographical "culture" such as roads and vegetation is traditionally managed in 2D by the GIS community
• a lot of the VTP software development, especially on vegetation coverage and raw feature layers, is starting to resemble GIS functionality
• from the other direction, GIS tools are attempting to move toward 3D, but are still fairly early in that process
• how can the terrain visualization field leverage or take advantage of existing GIS tools?

GIS Software, Open

• QGIS and gvSIG are among the most prominent of the open-source GIS tools
  • They both run on desktop and mobile, both read a myriad of formats and have decent user bases.
  • As of 2012, gvSIG has the more extensive 3D support.
• GRASS
  • "raster, topological vector, image processing, and graphics production functionality"
  • Includes some 2.5D and 3D visualization capabilities.
  • Unfortunately, it bears a lot of historical baggage; from 2002 to 2010, despite repeatedly attempts and much effort, i did not manage to get it to open any dataset.
  • For those who do manage to get GRASS working, there is an interesting module NVIZ with some virtual terrain capabilities: "NVIZ allows users to realistically render multiple surfaces in a 3D space, optionally using thematic coloring, draping GRASS vector files over the surfaces, and displaying GRASS site files either draped on the surfaces or as 3D point locations."
• SAGA
  • An open-source GIS application with an emphasis on scientific grid and raster functions: digital terrain analysis, geo-statistics, image processing.
  • Imports all of the GDAL formats, exports ArcGrid and Surfer. Has an API so that people can easily add modules to it.

GIS Software, Closed

• ESRI ArcGIS (around $1000 for the entry level)
  • The most widely used GIS package, usually sold through dealers / resellers.
  • For 3D, there is add-in called 3D Analyst (see Commercial Tools)
• MapInfo ($2000)
  • was the leading competitor to ESRI, but now FOSS packages like QGIS are a more relevant alternative
  • some 3D possibilities exist with the optional Vertical Mapper (~$1200?) which from the marketing literature doesn't sound as impressive as 3D Analyst
• Maptitude ($700)
  • a lower-cost alternative to the "big two", has all the usual 2D GIS functionality
  • as of version 4.5, it added some 3D support including the ability to turn contours into a heightfield and do a flyover
  • "Drape a map over a surface to see the map in three dimensions and control the display of 3-D maps with the new 3D Toolbox."
  • 3d operations: calculate spot heights, viewsheds, shortest path over terrain
• Manifold ($300 and up, Windows-only)
  • A very low-cost GIS package that claims to have all the same features as the other more expensive tools, e.g. ArcGIS and MapInfo
  • consists of a large suite of products, "3D visualization is a built-in part of every Manifold edition"
• Cadcorp SIS ($?)
  • From the UK, seems full-featured, and reportedly compliant with OGC standards and specs
• fGIS
  • a freeware GIS (Windows only) once with an emphasis on forestry, but as of 2005 a general-purpose GIS
  • supports a huge number of raster and vectors formats; seems to do a wide variety of common GIS tasks

 GIS Data Formats

• ESRI Shapefiles (SHP)
  • these are output from the commercial GIS tools ArcInfo and ArcGIS (historically, ArcView)
  • it is a very common format for geographical coverages such as land use, vegetation, etc.
  • it contains "vector data" which can be point, lines or polygons
  • documented in an ESRI whitepaper: Shapefile Technical Description
  • consists of up to 4 files:
    • .SHP - main file, contains geometry only
    • .SHX - index file, always accompanies the .SHP
    • .DBF - database file that contain attributes for each entity in the SHP file
    • .PRJ - contains projection information (only rarely encountered)
  • there are many available libraries which read and write SHP/SHX/DBF nicely
• ESRI ArcInfo Export files (E00)
  • a proprietary, inefficient ASCII format which is exported by ESRI's high-end ArcInfo program
  • there is no official documentation, but some ArcInfo E00 Format Analysis
  • it can contain either vector or raster data
• MapInfo files
  • file extension for their "interchange" format is .MID/.MIF
  • standard binary form ("TAB") has extensions .TAB, .DAT, .MAP, .ID, .IND
  • can be read by the MITAB library, which is part of the OGR library
• There have been many proposed "replacements" for the ubiquitous Shapefile format, but no clear leader.
  • SpatiaLite is a relatively new GIS file format based on SQLite, which uses a single file to store multiple layers and data tables.
  • As of December 2012, there is the OGC Draft 'GeoPackage' Specification.

GIS Data Model Standards

• traditionally, there has been no standards for GIS attributes making data interchange of real-world data prohibitively complicated in general
• ESRI has begun the process of defining 'ArcGIS Desktop Data Models'
  • the good news is that there are 19 areas, and it looks to be growing
  • the bad news is that the standardization is strongly oriented toward
    abstract values rather than physical descriptions, although there are some
    very low-level physical details e.g. the Pipeline Datamodel defines
    attributes for 'OutsideDiameter' and 'WallThickness'
  • probably the most relevant area to the VTP is their Basemap Data Models such as for Transportation and Hydro, although these appears to be just draft examples so far
• Generalizing GIS: Development of Spatial Grammars for Landscape Planning (pdf), Kevin Mayall and G. Brent Hall
  • proposes the odd idea of using shape grammars (more commonly used to describe buildings or cities) as a way of generating or analyzing general GIS data