I am hoping this surveying community can lend technical expertise on this topic.
The web is rife with recreational GPS users mapping trails with watches, smartphones and the like. The MTB community is one of the strongest proponents of creating trail data. USGS absorbs these data and has discussed this as an approach to "map trails". See https://www.imba.com/news/us-geological-survey-partnering-imba . I humbly disagree. My opinion is to tie any professional GIS representation of trails with mapping grade GPS that ties data to CORS and hence the NSRF in both horizontal and vertical reference frames.
I output positions(GIS call these vertices) along a trail line in Geographic (Lat/Long) and orthometric height. I enter said coordinates into an Excel macro that produces 3D distances between these positions and graph these for publication along with the linework for 2D maps. There is much controversy that we (GIS) should not be doing this. We should be using RTK etc. Yet, I think my mappers, with good skills, excellent hardware can produce the 3D distances over any length of trail that mimics Ground distance over any trail of any length - quickly, efficiently, and with attributes demanded by facility managers. Simple geometry says the hypotenuse between two positions can be calculated to produce slope distances A logging rate commensurate with trail nuances can provide such data that is precise for very large mapping scales.
I'll share my Excel macro (designed by my Civil Engineer cousin) and the process for Trimble Pathfinder Office workflows for anyone to test. Basically, Lat,Long,Elevation in a CSV is all that is required. Email me at [email protected]
Am I committing survey heresy by such an approach? Are you as surveyors being asked to produce "ground" trail distances and have solved this dilemma for the public?
That can be done with a PM3 using Mobile Mapper post processing.
A Harris. Good to hear some support.
To quote how USGS will use recreational biker data to place onto 1:24K quads...."The 2014 editions of official USGS products covering Arizona will be the first maps to feature the trail data. Arizona will be followed in order by Nebraska, Missouri, Nevada, California, Louisiana, New Hampshire, Mississippi, Vermont, Wyoming, Connecticut, Massachusetts, Illinois, Rhode Island, South Dakota, Florida, Alaska (partial), and the Pacific Territories in 2015."
Are there not enough surveyors and professional GIS mappers out there in support of this type of work. I use Garmins... alot up here for certain navigation projects, but trail mapping for Topographic quads?
GISJoel_GetItSurveyed, post: 393319, member: 11867 wrote: Are there not enough surveyors and professional GIS mappers out there in support of this type of work.
I would love to be involved in this kind of work; where do I sign up?
Dougie
i'm with RADAR - anything that involves both mountain bikes and surveying and i'm good for some help.
familiar with both, but not so much with sub-survey intsrumentation, i'd be a little dubious as to the mapping capabilities of ANY GPS (survey-grade included) in certain circumstances, even at the scale and end use for which this is intended. for instance, i was just up in norcal last month riding and one morning did a 5 mile climb that might have been half a mile as the crow flies, climbed about 2000', was comprised entirely of 2-300' switchbacks, and was 100% covered by thick canopy. there isn't an antenna on earth that will make quick, accurate work of that.
florida, though, is a different story.
There must be multiple units setup over control points while a separate unit is used as the rover for it to even be close.
The distance from control points is different for some makes of GPS units.
Post processing is also necessary for better results.
And in the end, it will not be completely foolproof.
Some points will fail.