Digital Mapping





Landsat image of the Missouri River



Updated 26 June 2006

Jack A. Caldwell

Technology Overview

Wikipedia defines aerial survey thus:  Aerial survey is a method of collecting information by utilizing aerial photography or from remote sensing technology using other bands of the electromagnetic spectrum, such as infrared, gamma, or ultraviolet.  It can also refer to the chart or map made by analyzing a region from the air.  This is typically done using satellites, aircraft, balloons, or kites.  Aerial surveys can provide information on many things not visible from the ground.





Topography of the Earth

Aerial surveys are used for:

·       Land survey

·       Mining

·       Archaeology

·       Monitoring wildlife and insect populations, called aerial census

·       Reconnaissance


A digital elevation model (DEM) is a representation of the topography of the Earth or another surface in digital format, that is, by coordinates and numerical descriptions of altitude. DEMs are used often in geographic information systems. A DEM may or may not be accompanied by information about the ground cover. In contrast with topographical maps, the information is stored in a raster format. That is, the map will normally divide the area into rectangular pixels and store the elevation of each pixel. In that sense, digital elevation model (DEM) data are sampled arrays of surface elevations in raster form. DEMs are most commonly used to extract terrain parameters, model water flow or mass movement or for pure visualization purposes (3D draping).

Digital elevation models may be prepared in a number of ways, but they are frequently obtained by remote sensing rather than direct survey. One powerful technique for generating digital elevation models is interferometric synthetic aperture radar; two passes of a radar satellite (such as RADARSAT-1) suffice to generate a digital elevation map tens of kilometers on a side with a resolution of around ten meters. One also obtains an image of the surface cover. Older methods of generating DEMs often involve interpolating digital contour maps that may have been produced by direct survey of the land surface. Note that the contour data or any other sampled elevation datasets (by GPS or ground survey) are not DEMs. A DEM implies that elevation is available continuously at each location in the study area.


Technology Application to Mining

Jamie Hansen in Aerial Surveying In Mining 2003: A Surveying Odyssey (PDF) discusses the evolution of aerial surveying, its tools, and its capabilities in regard to the mining industry.  He provides a snapshot of the “aerial mine surveyor” and speculates on the delivery and use of spatial information services to the mining industry in the future. 


NGRAIN is a patented interactive 3D visualization platform to build real-time interactive graphics applications ranging from military vehicle repair to mining simulation.


Websites provides services to the aerial survey and mapping industry ranging from training to services and d most anything else in between.


Aerial triangulation - determining exterior orientation elements of image blocks, object space coordinates of tie points from images, interior orientation elements, and control information



Here are some consultants you may wish to consult:


In Canada there is Aero Geometrics. They work less that a block from my office and very kindly spent hours of their valuable time showing me what they are doing for the mining industry.  Unfortunately they are so busy I was not able to get them to contribute to the technical aspects of this article, and they are too busy to fully update their website to display all the amazing things they do for mines.  All I could get was this list of services they provide:

·       Aerial Photo (photo mission planning and consultation)

·       Control and cadastral surveys

·       Photogrammetric scanning and aerial triangulation

·       Digital mapping and terrain modeling

·       Update, transfer and mapping from satellite imagery

·       Cross-sections and profiles / Volumetric calculations

·       Orthophoto creation and mosaicing

·       3D Visualizations (including NGRAIN technology)

·       GIS data conversions & transformations.






NASA's AirSAR instrument is attached to the side of a DC-8


In the United States Tobin merits your attention. 


In South Africa AOC has this description of themselves:

AOC is an Airborne Remote Sensing, Digital Mapping and Geo-Information Company providing quality products and services to South Africa and the African Continent since 1931. Our services and products include Aerial Photography, Digital Orthophoto Imagery, Digital Terrain Modeling and GIS Solutions with an emphasis on up to date technology with on-going research and development.


Australia has Qasco and the United Kingdom has Photarc Surveys.  





In Alaska there is AeroMapUS which describes their mining work thus:

A continuing challenge for the Alaska mining industry is to develop better methodologies to identify exploration targets, delineate wetlands, identify cultural resources, quantify disturbed acreage, and track reclamation activities.   Remote sensing techniques and resultant map products can be a valuable asset for internal purposes and for communications with State and Federal regulators.  AeroMap acquired controlled aerial photography and multispectral imagery of the Fort Knox Mine site to assist in these objectives.  The aerial photos were used to produce a high-resolution orthophoto, which was subsequently used to register a mosaic of the individual multispectral images.



Digital elevation model of terrain surrounding the Chino Mine, NM