How many still set up a grid to follow when performing topo surveys in heavily wooded areas? Or do you just snake your way through the site and pick up ground shots where possible, and at some sort of spacing? You'd obviously make sure to locate major features (ditches, swales, etc.) in either scenario.
Thanks,
CC
I still walk a grid, but not like when we did them with auto levels.
The last one I did in the woods was so thick, I had no choice but to set a base line up and cut lines every 50' and get shots in the cut lines.
I've always just too shots where needed. I've even been given specs for the topo that say "50' grid". I've still just paced those to get a roughly 50' grid and never had anyone complain.
I'm like Kris, I generally walk a grid. In the woods, I use the bob and weave method, find the easiest shots with the least amount of leave/brush, but of course, picking up the required breaklines, ridges, etc.
It really helps when you draw them in the office. It makes you more efficient in the field.
I Put Some Cross Section Line Points In My Data File
This is for stream cross sections, the woods are relatively open and I will use "Stake to a line" in my data collector to get them close. After I have my grid line shots I will fill in with other shots to fill out the topo.
Paul in PA
I follow lines of features such as creeks, swales, and ridges, then shoot the trees and other objects that don't represent linework, and lastly fill in with ground shots where needed. Since topo features and countours rarely do us the courtesy of following a grid, I feel that better representation of the ground is achieved radially by following the features.
If the client wants to see elevations on some arbitrary grid pattern, those can be generated easily enough, with a note included explaining the grid elevations and mapping accuracies.
Catch all the breaklines and whatever else you need to make the DTM.
If the client insists, reverse engineer a grid for them.
I do a sort of blend. I pick a baseline. Then I walk lines taking a profile at offsets from the baseline (stakeout line). This fills in the grid but not on a perfect square system. As I go I pick up other features close to where I'm at. I also take the needed breaklines, usually walk them so they are all together in the file coded. I rarely paint of flag anything, I know where I've been according to the offset I'm working. This is GPS type work, wouldn't work in the woods.
I always try to do a grid as well as locating features and break lines. Call me old fashion, but I believe that standard specks demand you do a grid on all topos as well as obvious features such as top of bank etc.
A topo is only as good as the number and spacing of the shots you get. If you want a less accurate topo take less shots.
Quit the grid in 86. Never looked back.
And...do you paint your shots?
> And...do you paint your shots?
Never. No need if you know what you are doing. In dirt, kicking the dirt up a bit for a 'last shot' for an area is good enough. On paving we may mark a 'last shot' with chalk, but never ever will they be painted.
We had a project where the crew chief painted EVERYTHING and I got a call from some of the shop owners along the highway-boy were they upset.
Anyway, had a talk with him, restricted the painting and got more temporary paint for when he really needed it. Also had a crew chief who painted everything during some large topo's he was doing (50-100ac); sites for reservoir design. He went through a remarkable number of paint cans. I went down to fill-in and did one of the larger sites and didn't use any-but it was pretty simple, just ground, no utilities. And with the map function you can see what's missing.
In the manly Florida tangle-jungle, you have to cut the bleeding grid lines and then get as many shots as you can.
There ain't no: "I'll just follow this contour."
You're lucky if you make it out of there with your life.
Have not really thought of it, but in general I only grid in open areas. Otherwise I tend to shoot the objects in groups, which may involve more walking, but helps me make sure I get all the items. Then I tend to end with densifying areas that need it.
I just like your avitar! Looks like a surveyor to me!!
🙂
N
Yeah, sometimes it's nice to work were each tree has plenty of room to branch out.
> I just like your avitar! Looks like a surveyor to me!!
>
> 🙂
>
> N
It is. That's TDD.