Web Sites for Raster Data
As collected and assessed by FRST 122T students
URL: http://www.gis.unbc.ca/courses/geog300/lectures/lect3/index.php
Value: 4/10
Description: I found this information on the UNBC website. I particularly didn’t like the way that the information was given on this site. It just gave a little information of what Raster data is. It talks about the characteristics, advantages and disadvantages, and that’s it. It then goes into the information on Vector data as well in the same sort of manner. It then goes on to compare the two types with pretty primitive looking diagrams. Then at the end it gives you a pitiful looking review section that only asks what the advantages and disadvantages to both types of data are. The site itself is pretty small, about 2 or 3 pages if printed. Not a lot of info given so if someone is truly looking to understand Raster Data, they wont with this site.
URL: http://www.sli.unimelb.edu.au/gisweb/GISModule/GIST_Raster.htm
Value: 10/10
Description: I found this information on the University of Melbourne website. It goes into very good detail about what Raster Data actually is. It tells you how Raster Data is actually used in the real world. This web site brought new terms to my attention and taught me about exhaustive enumeration and run length encoding. Not only does it tell you what these two are it gives good diagrams showing how they are used. The best part about this web site to me was the chart showing us the advantages and disadvantages to using Raster versus Vector and vice versa. The web site is cleanly set up and very easy to understand. You don’t have to download anything on this site, so there is no waiting around for information to download.
URL: http://www.ac.wwu.edu/~walkers/common/raster/raster.htm
Value: 8/10
Description: I don’t know what University this information is from but it was really useful. It wasn’t as much information as the Melbourne website but a lot more than the UNBC website. The site gives easy to understand words to describe what Raster data actually is. This site gives you the characteristics of the data also the most important thing to me on this site was it shows how the data is stored in the Raster grids. They talk about the numeric codes to the classes of information they represent. They also discuss the logical structure of the data and the plus and minuses of using Raster. There is nothing to download on this site so everything is right there. It is clean and easy to read.
URL: http://www.sli.unimelb.edu.au/gisweb/GISModule/GIST_Raster.htm
Value: 7.5/10
Description: This website is a very short description of the concept of raster data. It explains grid size and resolution, raster data structures, data capture, the conversion between raster and vector data, and compares the advantages and disadvantages against vector data. Although the information about raster data is basic and concise, each subtopic contains a link to a more in-depth explanation. The pictures are very easy to understand and may even be too simple. There is a helpful chart showing in which situations you would use raster or vector data. This website is easy to navigate and is clearly laid out.
URL:http://www.olemiss.edu/depts/geology/courses/ge470/gistop_8b.htm
Value: 8/10
Description: Topics on this site include raster data models, raster data structure, types of raster models, and the TIN model. The organization is not consistent, making it difficult to pick out which are main topics and which are subtopics. Also, the summary at the end of the page highlights different aspects than the subject titles at the top of the page. The information is very concise. Definitions are printed in bold, making them easier to pick out. The illustrations are very helpful, but are only shown when you click on the associated link. It also outlines the applications of raster outside of GIS.
URL: www.utdallas.edu/~briggs/poec5319/struct.ppt
Value: 8.5/10
Description: This website features a PowerPoint lecture on GIS data structures. Although the information is very in depth, it does an excellent side-by-side comparison of vector and raster data. It uses multiple examples to illustrate the benefits and disadvantages of using raster or vector under different circumstances. Since it is a PowerPoint lecture, there are no table of contents to direct you where to go, and you must scroll through each slide before you find the one you need. Even though it is a lecture, the slides are useful and self-explanatory. The pictures are especially helpful in explaining the differences between raster and vector data structures.