In issue 2 of SpatialNews we offered a
comparison of ArcView
and Mapinfo. I thought a good follow-up to this would be to discuss the
features of the associated 3D analysis and raster based analytical
tools - 3D Analyst & Spatial Analyst by ESRI, and Vertical Mapper
by Northwood geosciences.
Spatial Analyst (SA) is used for spatial modelling and analysis,
enabling you to query, map, and analyze cell-based raster data
and to perform vector-raster analysis. SA allows users to
incorporate the results of the 3D Analyst extension into the
ArcView environment for further analysis and manipulation.
Some of the functions of SA include:
- convert themes to grids
- raster buffers
- generate surfaces from points
- create contour, slope, aspect, and hillshade maps
- neighbourhood operations
- grid classification
- mathematical calculations on multiple themes
An example of an application you could cdonduct using SA would be
to create a colour thematic elevation map with hillshading applied.
Topographic (vector) features could then be overlaid and a proposed
pipeline displayed. You could then easily generate a graph that
depicts the vertical profile of the proposed pipeline based on
elevations of the grid.
3D Analyst (3DA), an ArcView extension by ESRI, is a tool for
creating, manipulating, and displaying 3 dimensional surfaces.
The product supports TIN networks and interactive perspective
viewing. With 3DA you can do the following:
- create 3d contours
- create surfaces from attribute data
- integrate CAD data
- statistical analysis
- create 3d surface models from GPS point data
- model real world features such as buildings
- combine 2D vectors with 3D surfaces
- interactive perspective views
- view shed analysis
- surface area, volume, slope, aspect, hillshading
- rotate, tilt, and perform fly-through simulations
- spot height interpolation and vertical profiling
- calculate surface area and volumes
3DA supports grids, TIN and 3D shape files. You can import data
directly from USGS DEM, and NIMA DTED formats and TIN models can
be created from ArcView themes. To give your data an even more
real life look you can incorporate and drape air photos and satellite
images onto your surfaces.
Vertical Mapper, from Northwood Geosciences - contour
modeling and display software which works seamlessly with Mapinfo.
VM is used to create raster grids from point and vector data using
a variety of mathematic techniques. You can also produce TIN models
and create grids from a variety of DEM formats including:
ASCII point, CRC500, DTED (NIMA), GSC, Geosoft, MONA (Europe),
Ordnance survey, USGS DEM, SDTS (USGS standard format).
With VM users can combine and mathematically overlay raster grids
to explore the relationships between them. Countours can be
produced from points or grids. A variety of colour ramping
techniques are available for thematic colouring of grids. For
final product output, users can add Mapinfo vector elements and
text can be added to the surface. Chose a line of sight, viewing
distance and elevation in order to alter perspective views.
Mapinfo Corporation boasts the "Top Ten reasons to use VM" as:
- interpolation from points
- ocation profiler
- trade area (Huff) modeler
- viewshed analysis
- colour and display grids
- use grid to update MI .TAB data
- statistical data aggregation
- Thiesen polygons
- access data with translators
Requirements of Vertical Mapper are MI 4.x, Win 95 or NT,
27 meg space, SVGA display. Vertical Mapper is now at release 2.1
Here's what users of the products liked/disliked:
- Its fairly well established - tested & proven
- Would like to export to USGS DEM
- Large user base and excellent support on Mapinfo-L
- Like the price!
- Rapid processing of large datasets
- Can't do kriging
- Supports many data formats for importing
- Ability to merge DEM files
- Easily imports USGS DEM and SDTS raster formats
- Ease of use & well documented
ESRI - Spatial Analyst & 3D Analyst
- Many people require both SA and 3DA and feell $$$ is too high
- Get lost when rotating perspective of 3D scene
- Problems printing out of Spatial Analyst
- Poor documentation
- SA - Rapid execution of calculations
- SA - Map Calculator is a joy to work with!
- Can't reproject grids
- Difficulties importing data when in Arc seconds ie. USGS DEM
- Excellent training available
- Many extensions freely available
- Uses ArcInfo GRID model
- Ability to create VRML scenes fast and easily
- Wish for a "simple measure tool"
- No directional reference when "spinning" in 3D
- Importing data can be challenging
- Lots of free add ons and excellent support on lists.
Well, there it is. Not alot of surprises revealed here, but
hopefully some usefull content for those of you thinking about
adding 3D mapping and analytical tools to your GIS. Please keep
in mind that these are not the only 2 products available that can
accomplish 3D mapping and raster-vector analysis. Each month I
get emails from people asking what other products weren't included
in the comparison - well, mostly its because I don't have enough
time, and secondly, these are the only two that I've used recently!
Something I would like to add, recently I downloaded and used
ImageWarp, a free Avenue extension. This puppy is great! It
requires SpatialAnalyst and is a breeze to use for georeferencing
airphotos in ArcView. The documentation is excellent, installs
very easily and the author will get back to you in response to
any questions or comments. Thanks again to Kenneth McVay,
Environmental Geologist, for making this wonderful script freely
available. You can access it at the ESRI ArcView scripts site
(link given below).
Here's some related web references you may wish to check out: