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
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.
The above two images were created for my LIDAR flood modeling graduate research project. The first image is before the flood scenario; featuring a color shaded relief perspective view pointing south east from the Northumberland Strait landwards across the Pointe Du Chene wharf. The second image is of the same color shaded relief perspective view but features a 2.55 m flood level super imposed on top of it.
The 2.55 m flood level was an actual recorded storm surge water level that effected this area during a winter storm on January 2001. The two images below show the same flood level and area but from an overhead aerial view. The first image is with an orthophoto and the second image is with the color shaded relief.
The two images above are of a portion of the small town of Shediac, New Brunswick. Each one is of the same spatial extent, however the one on the left is of an aerial photo of the town (1999) while the one on the right is a color shaded relief model created from high resolution LIDAR data (2003) using PCI Geomatica software. The LIDAR digital surface model (DSM) was part of a LIDAR flood modeling graduate research project.
Shediac is a small town located in eastern New Brunswick approximately 20 kilometers north of Moncton. The town calls itself the “Lobster Capital of the World”, hosts an annual lobster festival every July, and the world’s largest lobster sculpture is situated at the main entrance to town.
The two images above represent artificial 3D perspective views from different points of origin featuring color shaded relief models that were created from high resolution LIDAR digital surface models as part of a LIDAR flood modeling graduate research project. The image on the left highlights a highway overpass while the image on the right features a residential area with a large school and a church easily detectable in the LIDAR all hits data set. Bouctouche is a small town located in eastern New Brunswick approximately 40 kilometers north of Moncton where the Bouctouche River meets the Northumberland Strait. It was an important aspect of the research study due to the extreme storm surge flooding that the region experiences every winter.
[*image source: PaulIllsley.com]
The following images are examples of perspective view models that were generated from a 2 meter LIDAR DEM integrated with 50 cm digital orthophotography of Port Lorne, Nova Scotia. Port Lorne is a coastal community along the Bay of Fundy with a relatively steep terrain so the images represent different perspective views depending on the source of origin and the direction that they are facing.
The colored arrows on the key image to the right represent the different perspective views that were generated from different locations and viewed along different directions (displayed in the images below). This image of the area also represents the traditional GIS view from above, as discussed above.
The first image below represents a perspective view (red arrow) of the area if it were viewed from the center of the image, above the wharf looking in an easterly direction.
The next two images below represents a perspective view (blue arrow) of the area if it were viewed from the upper right hand corner of the original image in a south west direction. The images that demonstrate the same perspective but have different types of LIDAR DEMs integrated with them allowing them to portray different data within them.
Most imagery (and/or spatial data) that we view in geomatics is typically viewed vertically downwards from the source toward the map or image. This typical aerial view that we are accustomed to using, allows an abundant amount of information to be represented spatially within a two dimensional cartesian representation. However, occasionally it is useful for us to change our focus from the default traditional view and use a more complex three dimensional visualization view of the data.
This type of terrain model is commonly referred to as a perspective view and often reveals additional information by allowing us to observe the same data obliquely.. In order to do this each location of the image needs to be transformed from the traditional 2-D to a 3-D projection coordinate system.
A perspective view is not really a new tool as it has been around for centuries, but it has become a popular component of most geomatics projects. “A Perspective is a rational demonstration by which experience confirms that the images of all things are transmitted to the eye by pyramidal lines. Those bodies of equal size will make greater or lesser angles in their pyramids according to the different distances between the one and the other. By a pyramid of lines, means those which depart from the superficial edges of bodies and converge over a distance to be drawn together in a single point” (Leonardo da Vinci)¹.
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.
Sample image on the right is a 3D perspective view of Cape George, Nova Scotia (just north of Antigonish), created with LandSat imagery drapped over a digital elevation model (DEM).
[* quote 1 is from – O’Connor and Robertson (2003) Mathematics and art – perspective www-groups.dcs.st-and.ac.uk/~history/HistTopics/Art.htmlJanuary]
3D color shaded relief (CSR) digital terrain model (DTM) of Bouctouche, New Brunswick created with LIDAR point data.
