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Geomatics – GIS Spatial Modeling

GIS Model of Average Annual Precipitation of the Annapolis Valley, Nova Scotia

GIS Spatial Modeling is the process of modeling, examining, and interpreting geographic data.It uses a set of defined methodology and analytical procedures to derive information with spatial relationships between geographic phenomena. It can be useful for evaluating suitability and capability, for estimating and predicting, and for interpreting and understanding real world situations. There are four traditional types: spatial overlay surface analysis, linear analysis, and raster analysis.

Data with spatial relationships can be modeled in a GIS to provide images and relationships that can be interpreted to help solve problems and provide information in a way that data bases by them selves can not. The image to the right for example is a screen capture of a GIS thematic spatial model created from a database of precipitation measurements from various weather stations and data loggers spread out across the region. ESRI Geostatistical Analyst was used to create a model that can be easily used to depict the amount of precipitation that a community in the region would experience based on the data from the databases.

Spatial Modeling Examples

Below are two presentations that I gave on GIS Spatial Modeling, one is an informal more information based one that was used to train other students how to use the ESRI Geostatistical Analyst extension and the other is a more formal presentation that was open to all students and faculty at the campus.

CanadianGIS

CanadianGIS.com is an extension of my web site that I started back in 2005 after I noticed that there was a real need to have somewhere on the web to help find Canadian GIS resources. And although there were a few other websites starting around that time related to GIS, nobody else was really dedicating a site to Canadian GIS topics.

CanadianGIS.com logoThe site has evolved slightly since then with a few functions or sections being added to it or removed as time went on but it has always been primarily used to promote the Canadian GIS & Geomatics Industry and to share information with other Canadians that also have an interest in GIS. It also went well together with GISjobs.ca, another GIS site that I created to help Geomatics students find Canadian GIS & Geomatics related jobs much easier. GISjobs.ca turned out to be a real success and eventually led to the creation of GoGeomatics, another Canadian Geomatics job board site that allowed people to post GIS jobs for free (now is fully fee based).

CanadianGIS.com helps provide people with resources about Canadian GIS & Geomatics related data, basic information about Canadian companies that provide geomatics services, locations of Canadian data and maps, information about GIS conference & events, places to find Canadian GIS employment and education info and many other great resources. Content for the site been created by me and a few volunteers, with some also being supplied by various GIS companies and academic institutions.

If you have not yet checked the site out then I encourage you to go and see for your self, and if you discover that there is information related to Canadian GIS resources that I have missed then please do let me know. – Join the Canadian GIS LinkedIn Group (2200+ members) or the Canadian GIS FaceBook Group (2100+ members but mostly different from the LinkedIn group)

regards,

Ted MacKinnon -Geomatics Specialist

tmackinnon.com

Contact Me: email

Twitter: @tedmackinnon or @CanadianGIS

LinkedIn: tedmackinnon

FaceBook: ted.mackinnon

[page originally published in Jan. 2009]

3D Toronto Images

Below are a few 3D Toronto images from a demonstration that I gave comparing Esri Arc Scene with FLY in PCI Geomatica. I generated the digital surface model (DSM) from some demo LIDAR all hits data that we had. The coverage area is for a small portion of downtown Toronto centered around Toronto City Hall.

Toronto City Hall 3D LIDAR image made with ESRI Arc Scene

Toronto City Hall 3D LIDAR image made with PCI Geomatica

LIDAR all hits point data of downtown Toronto

3D perspective view with LIDAR all hits point data of downtown Toronto

Remote Sensing

Remote sensing is merely the science of acquiring information about a surface without physically being in contact with it. It involves the use of technical instruments or sensors to record reflected or emitted energy and then processing, analyzing, and applying that information to determine the spectral and spatial relations of distance objects and materials.

Remote SensingThis is possible due to the fact that the examined objects (such as vegetation, buildings, water, air masses etc.) reflect or emit radiation in different wavelengths and intensities according to their current condition. Modern remote sensing typically involves digital processes but can also be done with non-digital methods.

Probably the most common example of remote sensing is an aerial photograph but there are probably hundreds of applications related to remote sensing ranging from space-borne satellites to under-ground geophysical systems. It has become a major component in the evolving Geomatics industry. In order to generate maps for GIS, most remote sensing systems expect to convert a photograph or other data item to actual measurable distance on the surface. However, this almost always depends on the precision of the instrument that is being used to capture the data. For example, distortion in an aerial photographic lens can cause severe distortions when photographs are used to measure ground distances. Using sophisticated software like PCI OrthoEngine can convert the photograph into an ortho photo which can be used to measure ground distances.

In order to coordinate a series of observations, most sensing systems need to know where they are, what time it is, and the rotation and orientation of the instrument. High-end instruments now often use positional information from satellite navigation systems. The rotation and orientation is often provided within a degree or two with electronic compasses.

The resolution determines how many pixels are available in measurement, but more importantly, higher resolutions are more informative, giving more data about more points. However, large amounts of high resolution data can clog a storage or transmission system with useless data, when a few low resolution images might be a better use of the system.

Like I mentioned earlier examples of remote sensing are very numerous. I have over the past decade and have used the many projects that I have been involved with along with actual examples of my work to help illustrate the principals of the various topics covered on the web site. I have included basic overviews for each along with images, presentations, papers and links to other related resources.

Examples of Remote Sensing

Remote Sensing Links

GIS Mobile Mapping with ArcPad

Included here is a report written for an ArcPad / Trimble mobile mapping project, a presentation that covered all aspects of the project and more general information and links about GIS mobile mapping. The report includes all code used in designing the ArcPad application (visual basic, XML etc). The presentation was presented at COGS in Lawerncetown, Nova Scotia during the fall of 2003. The existing AGRG weather station network now consists of 14 tripods and 1 tower setups (as of Aug 2004).

Spatial Database Modeling of forest stands in Kejimkujik National Park

Here is a poster generated with ESRI ArcGIS for a summer GIS project that I worked on for Parks Canada. [The PDF technical report details the methodologies and issues that were encountered with a Spatial GIS vegetation database and GIS Spatial modeling project at the Applied Geomatics Research Group (AGRG) during the summer of 2004 that involved generating a spatial geographic database for Jeremy’s Bay Campground of Kejimkujik National Park and Historic Site. High resolution aerial photography acquired from a previous AGRG (COGS) aerial photography mission was used along with extensive data collected during a Rapid Vegetation Assessment survey and a detailed forest stand interpretation.]

Poster showing Spatial modeling database of forest stands in Kejimkujik National Park and Historic Site