Advocate Harbour Color Shaded Relief Map

A new large 8 foot color shaded relief map that I have created has been posted for display at a local tourist kiosk in Advocate Harbour, Nova Scotia. Now both tourists and residents of the area will be able to gain a better appreciation of the topography that borders the Northern Bay of Fundy region

Manuals for Leica Total Stations

Various user manuals that I refer to when working with Leica total stations (Some I created and others from Leica … ).

Geomatics Acronyms and Abbreviations

Geomatics has become a pretty common term in Canada lately and includes many different disciplines such as  geographic information systems (GIS), remote sensing, cartography, land surveying, global navigation satellite systems (GNSS), photogrammetry, geography and other related forms of spatial mapping.

Using acronyms and abbreviations is commonly practiced in the Geomatics industry and most of the time people just assume that everybody else knows what every acronyms and abbreviation stands for. Well that is obviously not the case most of the time and over the years I have created myself a little digital cheat-sheet of geomatics acronyms and abbreviations that I use with my work in my writing.

Here is a large collection of common acronyms and abbreviations related to the Canadian Geomatics industry: http://canadiangis.com/geomatics-acronyms-and-abbreviations.php

3D Modeling with High Resolution LIDAR

I created and presented this poster featuring LIDAR Color Shaded Relief model of Bouctouche / Shediac area of New Brunswick at the 2004 Geotech event that was held in Toronto.

Color Shaded Relief Models

Traditional images in geomatics are often two dimensional, meaning that all data in the image can be referenced by X and Y coordinates. 
Three dimensional color shaded relief (CSR) perspective view of high resolution LIDAR

Three dimensional images (3D) incorporate a third dimension (the Z component) which represents the elevation or depth aspect of the data. To incorporate it into an image requires creating special geomatics value added products that allow users to perceive the presence of the third dimension into a traditional two dimensional setting (because most paper and computer screens are flat or two dimensional).

A color shaded relief (CSR) utilizes chromo stereoscopic techniques to help emphasize the depth of the Z dimension from traditional shaded relief models that already portray the presence of an elevation difference. Using carefully edited RGB (red, green, blue) pseudo colors and then encoding them into the shaded relief image provides the user with an even more enhanced feeling that they can perceive a third dimension from a two-dimensional medium (also helping to quickly decipher between high and low elevated regions). When a feature of the same color in the image is shaded darker than the shade of its background, then the background color will predominate in determining its perceived depth position in the image.

Color shaded reliefs utilize chromo stereoscopic techniques to help emphasize the depth of the Z dimension from traditional DEMs

There are several different software packages that can be used to create CSR models, but I have found that Geomatica software by PCI Geomatics has proven to produce some of the better results in CSR models generated from DEMs. ChromaDepth 3-D glasses can often be used to further enhance the three dimensional feeling as well. These glasses use sophisticated micro-optics technology to transform color images into stereo 3-D. If you do not currently have PCI Geomatica then you can obtain a trial copy of it from their web site; then follow the steps outlined in the following CSR tutorial.

Here are some more  Examples of some of the many color shaded relief (CSR) models that I have created

Orthophoto & LIDAR CSR for New Brunswick

Color Shaded Relief related documents:

 

Digital Elevation Models (DEMS)

Digital elevation model (DEM) of Lismore, Nova Scotia

A digital elevation model (DEM) or sometimes referred to as a digital terrain model (DTM) is a quantitative representation of the topography of the Earth (or sometimes other surfaces) in a digital format. They are a common component of geographic information systems /remote sensing and are usually represented by cartesian coordinates and numerical descriptions of altitude. In contrast with topographical vector maps, the information is stored in a raster format. That is, the map will normally divide the area into a rectangular grid of cells or pixels and store the elevation of each one as a DN value.

Traditionally most common DEMs used in the Geomatics industry only contain elevation values of the true ground’s surface but DEMs can also sometimes contain other features found upon the ground’s surface as well. When it contains all features it is often referred to as a digital surface (DSM). Digital surface models contain elevation values representing the ground as well as any other objects such as buildings and trees.

The resolution of the DEM, or the distance between adjacent grid points (often the size of the cell or pixel), is a critical parameter in determining the amount of detail that a user should except to represent in the DEM. The smaller the resolution, the more details or features that will be present, e.g. a 1 m resolution DEM will contain more details then a 20 m one and be better suited for hydrological analyses.

DEMs are used as a source of elevation (and to create other digital terrain models) for many different purposes such as:

  • to orthorectify imagery
  • as a source of topographic information and to create contour lines from
  • to identify geological structures in topography
  • to identify risk areas and hydrological flow patterns
  • to identify flood risk areas
  • to determine accessibility
  • to identify regions of visibility for radio or cell towers
  • to predict how the terrain can effect signal strength and reflection
  • and many more uses

Digital elevation models may be prepared in a number of ways, but they are frequently obtained by remote sensing rather than direct survey. Older methods of generating DEMs often involved interpolating digital contour maps from aerial photography produced by direct survey and interpretation of the surface.

Many mapping agencies produce their own DEMs, often of a higher resolution and quality, but frequently these have to be purchased, sometimes at considerable cost. The two methods of creating DEMs that are covered on this web site deal with LIDAR and Photogrammetry methods.

 

Digital Terrain Modeling

3D model of Lismore WharfDigital Terrain Modeling is the process of simulating or representing the relief and patterns of a surface with numerical and digital methods. It has always been an integral component to geology related fields such as geomorphology, hydrology, tectonics and oceanography but over the past decade has also become a major component to non geophysical applications such as GIS modeling, surveying and land use planning.

Sometimes commonly known as quantitative geomorphology, digital terrain modeling is thecomputer processing of raster grid arrays of elevation data. Using Geographic information system (GIS) technology we can further enable terrain-modeling results to be combined with non topographic spatial data creating several value added products.

Terrain Models are derived from data represented by digital elevation models (DEMs) and can include shaded relief models,
slope and aspect models, perspective scene generation, and drainage basin analysis (and other models).

The physiogeographic characteristics of a surface can often be determined by elevation, slope, and its orientation, or aspect. Together they can virtually define the surface plane completely, and provide valuable information for land use planning and other aspects of geomatics.

Traditional images in geomatics are often two dimensional, meaning that all data in the image can be referenced by X and Y coordinates. Three dimensional images (3-D) incorporate a third dimension (the Z component) which represents the elevation or depth aspect of the data. To incorporate it into an image requires creating special geomatics value added products that allow users to perceive the presence of the third dimension into a traditional two dimensional setting
(because most paper and computer screens are flat or two dimensional).

3D CSR LIDAR of a highway overpassIn GIS applications it is often beneficial to add a texture component to the spatial data that will help the user get a feeling for the vertical depth of the data by emphasizing the elevation. To do this you need to create a shaded relief model from the DEM to model into the data.

Shaded relief models use a defined light source at a fixed location it indicate terrain displacements using a shadow effect from evaluating the aspect and slope relative to the light’s azimuth angle and altitude achieved with varying grey scale tones resulting in the darkening of one side of terrain features, such as hills and ridges (the darker the shading, the steeper the slope).

The shadow direction is affected by the light’s azimuth setting and shadow length is affected by the altitude component. The models provide subtle shadings which we naturally perceive as depth, helping to make the image look three dimensional. A drawback with this type of model is that depending on the placement of the illumination source, the eye and brain often see different things. Adding color to the shaded relief images utilizes chromo stereoscopic techniques to help emphasize the depth of the Z dimension of the data.

Color shaded relief models (CSR) are usually graded with a pseudo color ramp from cooler (darker) colors representing lower elevations to warmer (brighter) colors depicting greater elevations. Most imagery and data that we view in geomatics is typically viewed vertical downwards toward the map or image. Occasionally it is useful to change that default traditional view because additional topographic information can often be revealed by observing the same elevation data obliquely (commonly known as a three dimensional perspective view). Data integration and overlays are very common with perspective views because it allows traditional flat images to become new products by incorporating an elevation component and providing a new look at the same data.  It is also probably used more so for visual appeal then as another method of extracting data.

Toronto LIDAR 3DThe image above and to the left is a perspective view of a color shaded relief created from high resolution LIDAR using PCI Geomatica software. The oblique angle view point looking down at the image allows the observer to easily identify many of the data’s features such as trees, cars and buildings.

The perspective scene in the image on the left is a representation of an urban terrain model including buildings and other various features. It was created using ESRI ArcScene software and high resolution LIDAR digital point data. The artificial oblique view allows the observer to obtain a unique glimpse from above looking down in a southerly direction towards City Hall of downtown Toronto, Ontario.

More information on Terrain modeling and examples


 

 

 

Geologic Application of RadarSat S2 Mode Data in Northern Nova Scotia

The following image is a photo representation of a larger poster that I made along with Blair Sangster at COGS in March of 1999.

The project also included a detailed paper and presentation that was presented at the Center of Geographic Sciences Auditorium, in Lawrencetown Nova Scotia.

The project used RADARSAT S2 beam mode SAR imagery and ERDAS Imagine together to provide 3D models representing various geological terrain features.