US Survey Feet?

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US Survey Feet?

Postby Guest » Thu Dec 13, 2007 6:32 pm

Any chance of supporting US Survey Feet? (Used heavily in mapping, GIS, etc, in the US).

1 US Survey foot = 1200/3937 m = 0.304 800 610 m

See Wikipepdia
[ It seems posts with URLs are rejected (for some strange reason), so I can't give an actual URL... ]
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Re: US Survey Feet?

Postby JoePaiva » Thu Nov 26, 2009 4:02 am

It would be nice to support U.S. Survey feet. many "civilians" consider it useless, but to surveyors, cartographers and others, it is a significant difference, amounting to about two parts per million. Its origin is in the latter half of the 20th century, when the international foot was defined as International foot = [m] / 0.3048 or 25.4 mm to the inch. Due to accurate mapping of the United States in foot units by the U.S. National Geodetic Survey (google National Geodetic Survey to find their website which includes a U.S. survey foot vs. international foot discussion) historical documents now had different meaning for positions in the U.S. that were accurately determined. Thus the U.S. survey foot, using the old definition of U.S. Survey foot = [m] x 3937/1200 was born. It would be a service to many professions to support this conversion. You should know that software used by cartographers, surveyors, GIS professionals frequently support U.S. survey feet. But there is much software that doesn't resulting in appreciable errors in calculations when long distances are converted (a little over 12 inches in 100 miles).
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Re: US Survey Feet?

Postby convert-me.com » Sun Nov 29, 2009 12:00 am

Survey foot has just been added to our Distance and Length conversion page.
Sorry it took so long to implement you suggestion
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Re: US Survey Feet?

Postby Larue » Thu Jan 19, 2012 2:36 am

Thanks, I was looking for something like this!
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Re: US Survey Feet?

Postby dlwatib » Mon Sep 23, 2013 11:48 pm

I'm not seeing any difference between survey feet and international feet (normal feet).
A normal foot should be exactly 0.3048 meters. A survey foot should be approximately 0.304800609601 meters or exactly 1200⁄3937 meters. It is incorrectly computing as 0.3048 meters the same as a normal foot.
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Re: US Survey Feet?

Postby dlwatib » Tue Sep 24, 2013 12:39 am

I see now why I was getting invalid results for survey feet. I didn't notice that the default 'Number of significant figures' is only 4. This is very easy to miss and not what I, for one, would expect, especially when using a unit like survey feet that requires a dozen or so decimal digits to accurately express as meters. It is much easier to ignore digits that you aren't interested in than it is to realize that you are looking at truncated or rounded numbers (as the case may be) when you didn't intend for that to happen. Your site would be much more useful if the default was the maximum precision that was available and then people could set it lower if that's what they wanted to see. Also, they need to know whether or not they are looking at rounded or truncated numbers. Lastly, greater use should be made of scientific notation whenever the significant digits threaten to exceed the width of the display area. You're using scientific notation to display red shift, but not parsecs, light years and other astronomical units.
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Re: US Survey Feet?

Postby convert-me.com » Wed Sep 25, 2013 4:28 pm

You are right, the fact we're rounding off the numbers can be misleading. We'll think how to make that more clear.

On the other hand I cannot agree with you that we should display maximum precision by default. We believe that many visitors, coming for everyday conversions (e.g. from kg to lbs) will be more satisfied with a shorter rounded-up result.
The good news is we try to remember the choice of every visitor so once you set precision to maximum it should stay every time you visit convert-me.com, assuming you're using the same computer and browser of course.

Scientific notation issue is even harder. There are a lot of our site visitors who simply don't understand it. So we use it only as a last resort when regular number would simply not fit into any adequate space. :)
But I just thought we might add a special settings for visitors like you that would turn scientific notation for more numbers. Will it be helpful?

Thank you very much for the feedback, I appreciate it
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Re: US Survey Feet?

Postby apple4 » Thu May 22, 2014 1:04 pm

many "civilians" consider it useless, but to surveyors, cartographers and others, it is a significant difference, amounting to about two parts per million. Its origin is in the latter half of the 20th century, when the international foot was defined as International foot
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