4-wheeler topo

I've done them as fast as I can safely go. Staking roads later the catch points were always around a tenth from the theoretical. At that time I was using a Trimble 5800 which took a pretty good beating mounted on a mast on the ATV. If your just going to be generating a one foot contour map. I'd say go as fast as you safely can.

Probably has to do with shot spacing. I try to stay at 7-8 mph, as IIRC 7 mph will give you 50ƒ?? spacing on your shots, or thereabout.

The Nate Theory of gps on an ATV:

It's raining. Raining gps data. The faster you go, the less wet you get.

Going slower, results in more data, for your gps to track. 5 to 8 mph is kind of the sweet spot. If you loose lock, at 20 mph, for 20 seconds, it results in a large data gap. If you loose lock at 5 mph, for 20 seconds, it does not hurt as much.

The javad does topo in a mode called "trajectory, it does not use point numbers. It makes 3d points, with lines connecting,?ÿ (if lines are turned on).

It's very interesting I've re-run lines down roads, under trees, just to get a statistical look at it. I had already taken verified shots on the road. So I knew what was right.

It's a very powerful tool. And, it is useful.

N

Not sure why anyone would want to do a topo of a 4-wheeler.?ÿ Maybe if they wanted to make one of their own and be able to create a mold for the plastic parts.?ÿ That would require some very short distances between shots, especially?ÿ around holes for fasteners.

?ÿ

EDIT: :d 😯 😳 ?ÿ

Not GPS, but did some experimenting doing total station topo with the prism mounted on a moving remote control toy car. We found that the angles were recorded at the moment the record button was pushed, but that the distance was recorded at the next epoch. Therefore there was some latency between the recorded angles and the recorded distances.?ÿ If the vehicle was travelling fast, this became a large difference.?ÿ

Back in the old days, when I was younger we knew how to pickup topo points.

If you don't have a movie, it did not happen.

https://photos.app.goo.gl/udxCkjs4xvrrGVzo8

https://photos.app.goo.gl/sEshaJnB9Fa5JbAeA

The only problem at 30 MPH is hearing the data collector beep so you know points are being stored.

This particular job was 6 sections, 5 razors, 1 atv, 1 side-by-side. Worked out just fine.

Hard to say, but probably millions of acres have been topod using 4 wheelers and GPS. I don't know of a better way to do them, it's highly accurate, fast and comprehensive. Issues are mostly when there is too much relief and detail or too much land, then aerial topos work better and are cheaper.

We've worked on drone projects where it would have been much quicker to just topo it by the time all the targets were laid out and controlled, flights flown, data reduced.?ÿ

But very detailed ground is better flown.?ÿ

Frankly, I can't imagine how I would work without a 4-wheeler.?ÿ

There are two main ways to set-up collection, by time or by distance, by time is the only way to do a PPK topo which is a bit more accurate than an RTK topo which can use either way.?ÿ

move from 0-60mph, it doesn't make a lot of difference, do it safely is the most important issue.?ÿ

I've heard of 4wheeler based GPS topos but wonder how they can get down below 8"+- given the vehicle suspension travel and tilt errors.?ÿ But of course maybe that's good enough for rough topo, so is viable.

I've done quite a bit of mapping from a UTV.?ÿ Before RTK was introduced in the 90s it was done based on time and post processed. Now, for the most part, I use RTK on a distance basis.?ÿ I like to keep the speed in the 5 to 10 mph range on raw ground. Any faster and you you bounce too much resulting in bad data and damaged equipment.?ÿ In pavement I have done it at 60 mph.?ÿ I should note that I have had a mount break send a receiver to an early grave?ÿ

@mike-marks

I will always do random checks, they normally check between .05' to .1'. The last large pad I did the catches were either flat or within .01' when it was staked, I don't know of any other way to do it more accurately unless it's walking and taking individual shots as you do which would be 10 times slower. 

There isn't much suspension travel using our set-up, and we use hard sided tires, the soft tires are too much of a pain. And as far as slopes, it's an issue when the slopes are very steep, but then you are walking anyway, those are unsafe for 4-wheelers. 

Everything should be checked, you don't want to give out a topo and find that you put in 3.4 for an H.I. instead of 4.3.

@mark-silver

1.  Thanks for the fun videos.

2.  Who knew that there were different ways to pronounce the word “topo”?

The other reason to keep the speed down is navigation. I'm usually looking at the DC to maintain good spacing between lines for proper grids.?ÿ

@mark-silver

The second video is how it works for me, except I'm on a single atv, my receiver is mounted over the left side tire and the DC is mounted behind and near the center of the handlebars.

It is a problem to hear the DC.

I normally watch it, and I'm often changing descriptions so I get to check it and be sure it isn't losing connection or lock.

If it does I look at the record, travel back to the last good location and fill in missing areas.

It's also nice to be able to see on the tracks on the ground.

A light dusting of snow is the best condition for topo. 

I will pick out to points on the horizon and make grid connections to them, travel in parallel lines for flat open country like I see in your video, for more complicated areas it's mostly breaklines with random topo shots to fill in. That's when the map really helps. 

@mightymoe

This was my go-to DC holder.

I should have prefaced the video by saying I got a call at 6:00 pm on a Friday night asking if there was anyway to get the topo done by 5 pm the following Tuesday. Unlimited budget. We got'er done and it actually worked out really well. The resulting DEM was beautiful. I had concerns that with that much equipment we would have a hard time keeping the HI's on the rovers correct. The first thing I did was build a check-in station on a flat piece of concrete and we made every rover pull up and check in every two hours, storing a check shot with vehicle pointed both ways.?ÿ

We got away with one base location because I had two 35 watt repeaters. It was a pile of GNSS equipment to come up with at one time, and it really was a full time job just to charge batteries.

The crew I came up drank all the whiskey in town every night (it was an older group of licensees as Loyal would say) and nobody got hurt. I believe it was the biggest April week for the local establishment ever. Our pictures were still tacked above the bar when I stopped in last year.

The only thing that really slowed us down was working under the really big power lines and hand spotting 15 miles of ditch and ditch bank, top and bottom, both sides.

And of course, it took a long time to get paid because they did not understand that they were on the hook for 'everything'. But it did finally work out great. And the underlying project was so big that our whoop-tee-doo was just the lint in the project's pockets.

I have a few more great videos, but I don't know for sure that the language is suitable for this forum and I don't think any of the other guys want their faces plastered all over the WWW. It was pretty 'Western' as we say.

@mark-silver

Send me the other videos if you are willing...

not .01', 0.1'

@mark-silver

There are times to get "Western".

My set-up:

Iƒ??ve used survey pro in auto collect/ time mode. The agency requirements were no more than 25 ft between shots- so we tried for 5-7 mph. It all depends on what kind of accuracy /mapping standard youƒ??re going to certify.?ÿ

They should offer a combination mode, that would guarantee not more than X feet apart but also not more than T seconds. Then you could meet a distance spec but get denser points when you slow down for a creek or other terrain feature.