Subject: Re: elevation and geodetic system question
From: Creagh_Ferguson@msn.com (David & Lorri Ferguson)
Date: 10 Jan 97 23:53:41 -0800
NGS has a product available on-line at
http://www.ngs.noaa.gov/PC_PROD/pc_prod.html called CORPSCON. It
contains a vertical conversion routine for the nationally recognized
datums. You can also find at that site GEOID96, which computes geoid
height values for the conterminous United States, Alaska, Puerto
Rico, Virgin Islands, and Hawaii, suitable for conversion of NAD83
GPS ellipsoidal heights into NAVD88 orthometric heights. GEOID96 has
what amounts to a geoid table for the listed regions built in.
Subject: Re: autocad dotted font
From: carekio@nanaimo.ark.com (Chris Chierchio)
Date: Sat, 11 Jan 97 02:40:13 GMT
In article , magrls@netzone.com (Matthew A. Graham) wrote:
>In article <32D16815.2A5F@micron.net> BPorter writes:
>>From: BPorter
>>Subject: autocad dotted font
>>Date: Mon, 06 Jan 1997 13:01:09 -0800
>
>>I'm looking for a font that will produce the dotted look (sort of a
>>screen) for lettering on records of survey for background records
>>information calls. Can anyone tell me where, or if, that font might be
>>available ?
>
>Haven't seen a font that does that, but depending on what your plotting
>with, you can change the line color to plot a grayed out line similar to what
>you describe. Colors 8 and 9 (light and dark gray)appear hatched on my DeskJet
>and on the electrostatic plotters my service uses.
>
>Matt
>magrls@netzone.com
You should be able to set your linetype when plotting (under pen settings) to
allow for a dotted font. If this isn't convenient, e-mail me, I have a font
called dot font I can let you have.
Chris
Subject: Re: Civil Engineering students
From: "Peter & Carmel Spierings"
Date: 10 Jan 1997 20:33:00 GMT
Kent McMillan sums up pretty well what engineering students should know
about surveying. I would, however, like to add some comments which come
under the heading of
M e t h o d s o f S u r v e y i n g.
One quite effecient method of surveying, both in terms of economy and
reliability, is that of surveying by photogrammetry (aerial or
terrestrial). The main advantages of photogrammetry are:
The accuracy and its reliability can be readily pre-determined. For
example, I have often used the factor of 0.02% of the flying height (camera
to object distance) as a indication of what pointing accuracy can be
expected from a fully controlled single stereoscopic. This has been
verified on numerous occasions to be quite workable.
Using photogrammetry, one obtains an excellent overview of the area to be
surveyed, eg a construction site. This enables one to determine where the
main efforts of data gathering are to be concentrated. Also, with very
little efort and therefore negligible costs, the stereoscopic model can be
re-constituded for check- or additional measurements.
Now, with the implementation of GPS, the costs of controlling a
stereoscopic model have been greatly reduced. In addition, the latest
software for digital photogrammetry enables surveys (eg for volumes) to be
carried out by people who lack specialised expertise in photogrammetry.
What this means, at least in theory and to a somewhat lesser extent in
practice, is that specialised expertise in photogrammetry has been
eliminated. Engineers, geologists, environmental scientists and many
others, can now perform their own surveying and mapping. This is not
wishful thinking, it is already happening. This, however, does not relieve
the professional from the responsibility to ensure that the survey data and
the results of the processing are reliable.
