Web Sites for Datum &
Georeferencing
As collected and
assessed by FRST 122T students
URL: http://www.esri.com/news/arcuser/0401/datum.html
Value: 8
Description:
The first aspect of this web site that caught my attention was the use
of terms and wording that were not overly technical and easy for the average
layman to understand. All the topics on
this web site were divided into their own topics that had their own headings
allowing the web site to be read easier.
This site also gives reference to many older datum’s as well as ones
used world wide. It has a good diagram
depicting the earths true surface shape as well as two datum’s and how they
fit. Also it talks of how datums
developed and provides some information on computer programs that accommodate
datum differences. At the end of the
site there is a list of references that show that the website is backed by fact
and provides addition sources in the field of datum’s.
URL: http://www.mentorsoftwareinc.com/cc/gistips/tips0798.htm
Value: 7
Description:
My first impression of the website was not a good one. The font size chosen by the author, I found
was difficult to read. Other than that
this site has many interesting topics including how early surveyors mapped out
and developed for of the first local and worldwide datum’s. Further down the page the author goes into
the technical aspects of how today’s datum’s are developed and becomes quite
wordy and has the potential to confuse the novice GIS user. It also has a good explanation on why datum’s
are so different and why it is important to chose the most recent and correct
datum for the given area. The paper is followed by a lost of links that go to
GIS tips and more technical papers about datum’s.
URL: http://www.colorado.edu/geography/gcraft/notes/datum/datum_f.html
Value: 9
Description: The layout of this website was very well done. It had a table of contents on the left hand side and the main body of the page a summary of the topics. It uses wording that is easy to understand and to the point. There were many convenient aspects about this website, such as buttons at the bottom of each topic to “jump” back to the table of contents. It talks about the different shapes of ellipsoids used and provides links, which are topic specific. One of the topics is about geometric earth models and reference ellipsoids. It shows why the earth is not a perfect sphere and the progression of the datum world. It has a very good diagram showing the earth surfaces, included are the ellipsoid, topographic, and the geoid surfaces.