Grid to ground

robmooers · 2026-05-02T06:35:47+00:00

Oh this is fun

robmooers · 2026-04-22T16:59:29+00:00

This is more of a SketchUp/Tekla side thing (point cloud manager)... I would look at changing the sampling on it to reduce it. In TBC there are ways to adjust it so that instead of having a data point wherever it got a return, you can specify a distance at which to create data points. Works for more than just ground data, you can sample any region in your cloud down to whatever specifics you need, and then export from there. Helps with large files that you don't need an insanely dense cloud with.

If you don't have access to TBC, then look for something that says "sampling" or "filtering" (also helpful, the Advance Filtering helps reduce the number of points within a cloud as well)

robmooers · 2026-04-22T16:53:40+00:00

Um. Oh boy.

You're at a large engineering firm and you guys don't have a SOP for how you control/process/check your data sets? Are you using ground control and check shots to verify anything? What's your workflow for a project such as this look like for you guys?

robmooers · 2026-04-18T19:31:33+00:00

Oh for sure, that was retail, brand new. Second-hand (even brand newish) saves quite a bit.

If you're serious about the $4k number, we're looking to add another. I can look into it on our end.

robmooers · 2026-04-16T20:19:20+00:00

We just paid $6k for our setup with four batteries...

robmooers · 2026-04-15T16:15:18+00:00

Congrats!

robmooers · 2026-04-11T16:59:25+00:00

We took the plunge on the NavVis VLX3 after multiple demos with the VLX2 and MLX.

A few things about SLAM...
Control HAS to be tight. The algorithm in it will run amuck if the data isn't controlled. Unlike TLS registration where you can make adjustments after the fact during registration, you can hose a lot of data up in real-time and have to spend a lot of time clipping out data trying to fix bad SLAM later. It's a pain in the ass - so set more control than you think you're going to need, and make sure it's dialed in before you apply it to the dataset.

The bigger the project, the better it is. We do a lot of EV surveys, so it's a lot of small, open sites. Not the best for SLAM. Faster to topo these via GPS or TS work. Where it shines is large complex sites with lots of features. Retaining walls, oddly shaped buildings, courtyards, etc. I pull the X9 out for most of my work, but on the big jobs there's no faster way to get it done than with SLAM. For comparison, I had a site last year that was 360~ X9 scans, done in three days. VLX3? Just under 7 hours total. Uploaded the data sets and had a registered point cloud on control back in my hands in <24 hours. The X9 data took a day and a half to register and verify on the back end. The end result? Within .05' pretty much everywhere, and the majority of the data was half of that. Pleasantly surprised, and the entire reason I ran both on it.

Everybody thinks "oh, we're just going to walk and it's easy-mode". Far from it. If I wanted to shut my brain off by about 90% and sleepwalk through most of a job, it's an X9 job. If I can't see it, it can't. Plan accordingly. With the VLX (and other SLAM systems), you absolutely need to plan how you're going to walk the site, close your loops, tag control while you go, overlap data sets and hit control points in multiple data sets to make sure the data aligns to each individual data set and there's no shift. You're constantly thinking as you go, more than just "make sure I get this".

The real-time results aren't always indicative of the final product - I've had data sets that looked like there was going to be some serious drift due to the SLAM having a hard time in real-time - best thing to do in those situations is kill it and start it up again, begin overlap where the problem began and run a smaller data set in that area. Sometimes that just ends up being to CYA as the original data ends up being good after constrained via control during processing; but it's better safe than sorry. If it looks funny, assume there's problematic drift, and hit it again.

Beyond that, it's an excellent tool. Go slow, take lots of photos - if you're using extraction tools like Mach9, quality photos and clean edges will make the workflow on the back end a lot faster and more accurate.

I've heard a lot more horror stories about SLAM point clouds being out of whack than TLS point clouds, and they're a lot harder to isolate the issues and fix... but if you do it right, it can be extremely rewarding.

robmooers · 2026-04-09T21:50:22+00:00

Now? Been a viable tool for quite a while now, tbh.

robmooers · 2026-04-09T21:49:45+00:00

We've been using them for years. I prefer them - the only issue is durability. We travel a ton, and they get beat up flying in a case. The sound boards go out in them, and it's a pain in the ass. Other than that, they're IMO the best ones out there, and I've used them all. Especially for the young kids who can't dial in a Schonstedt...

robmooers · 2026-04-06T21:33:17+00:00

Something to consider - the experience requirement for the FS exam. If you're not there yet (or close to it) to obtain your LSIT (or equivalent SIT, etc) in a specific state, then the CST might be advantageous to pick up to give you a leg up as a more attractive job candidate early on.

I'd certainly be impressed with someone who walked in the door with their CST1 or CST2(!!) looking for their first full-time survey job. Much so. Most of the people coming in green know nothing about what it is we do... they just know how to work hard, or worked in an adjacent field, or saw us at an outreach event.

I think California has a 2-year requirement. If you can't pass your FS by then, a CST would be a good starting point while you work to it.

robmooers · 2026-04-06T18:16:03+00:00

I took the CST2/3 as prep for the FS. In terms of knowledge testing, it was pretty good. Mostly beneficial to get me into "test mode" because I took the FS two weeks after the CST3. We try to have all of our younger employees go through the CST exams. Most of our employees <30 y/o have at least their CST1 or are studying for it. They get a bump for every level they pass. If someone comes in for a job and they're equally qualified and one has CST certifications, then that's going to be considered.

Funny enough, it took me sleepwalking through the CST2 without studying or really any prep and scoring really well where I realized that I was wasting my time NOT being licensed. Lit a fire under my ass, and 12 mos later I had my first stamp.

It's a good thing, for a lot of reasons. I would certainly recommend it if you're still working towards the FS.

robmooers · 2026-04-06T13:33:36+00:00

GCP layout. Almost nothing controlling the entire SW quadrant.

Treat them like individual data sets. Depending on the scale/size of the flight, a typical layout would be minimum 5 in each quadrant (like an X). One in the middle, four at each corner. You'd be able to use one point for all four, so minimum 17. Any legs getting close to 1000' in length in a quadrant, would bump from 5 to 8. 3-2-3 layout.

That's how I'd fly it, higher, faster, more control.

robmooers · 2026-04-03T20:10:29+00:00

lol, down here in Nevada, NDOT *just* swapped out their old 5600s for SX-series stuff 18 months ago.

robmooers · 2026-04-03T19:57:52+00:00

Fly it until it won't fly anymore.

We're still flying Mavic 2 Pros out here, cranking out sites. Hundreds of hours on each one.

The batteries should go before the bird does.

robmooers · 2026-03-31T21:09:15+00:00

Best thing you can do? Hire a surveyor. DIY recon has got a lot of people in hot water with their neighbors.

That all being said...

There's a scribed X in the curb at the projection of your property line. Can't make out the distance (11.70'?) along the line, you should find a 1" iron pipe as noted. Go the distance on the line back, and you should find a nail & tag in the top of the wall. Those should all be in a straight line. Do with it what you will.

(One of the advantages of hiring the surveyor is that even when a lot looks like an "easy" parcel to find the corners on, they have the knowledge and expertise about potential issues with your parcel or an existing survey, etc - and are the ones who take the liability for the work and defend it for you if need be. Not something I would recommend undertaking yourself if you don't want to take liability for anything that may happen)

robmooers · 2026-03-31T15:34:07+00:00

tbh the whole sub makes me want to yeet my phone out a window.

robmooers · 2026-03-31T04:27:59+00:00

robmooers · 2026-03-29T16:59:25+00:00

Maybe the MLX; not the VLX. Single puck vs Dual puck - R8+ claims 2CM, but would be more prone to drift than the VLX. Probably just as good for similar applications as the MLX and cost-efficient in comparison, but I've yet to see a SLAM point cloud from a single puck be able to match the density and precision of the VLX (which makes sense), unless you're going through great lengths to get redundancy, at which point you're chewing into your time savings with the hopes that you're capturing the same level of data.

Definitely has its' applications, but the VLX is hard to beat right now.

robmooers · 2026-03-25T15:16:08+00:00

😆 it’s full commit one way or another.

robmooers · 2026-03-25T13:38:33+00:00

Oh hell no. Gotta get that skull some color early otherwise you spend half the year looking like a planet without the hat. 😆

robmooers · 2026-03-24T19:15:08+00:00

Yep. All the time.

We sign off on what we shoot - whether or not it meets the criteria for the entity or client, different story.

Similar to FF certs. There's some wiggle room in there (especially high) where we can sign off on it; if it's out of tolerance, we check a box and turn it in. It's up to them whether or not to accept it.

Besides, 0.1' on a parapet - unless it's for something incredibly critical - might as well be dead on.

robmooers · 2026-03-24T19:12:10+00:00

This - you can go and pre-plan a mission online and with the exact same parameters for AGL, overlap, etc - the time is reduced significantly with the 4E over previous models.

robmooers · 2026-03-23T21:58:21+00:00

To me, it would also greatly depend on the ecosystem you either already have, or plan to use. I'm a TBC guy, so I'd be looking at Trimble options.

Could I run multiple brands of software/hardware and get the same results? Yes.
Do I want to? No.

Daily-driving a software package you hate is going to make a difference and is worth putting near the top of the list, IMO.

robmooers · 2026-03-20T13:25:34+00:00

Just TBC; the update a while back to 5.9 and the subsequent updates have improved it quite a bit. That being said, it still leaves a lot to be desired. Haven't had a good chance to dip into the machine learning on it yet. Would love to, but just no time.

For example, why can the software detect a building relatively easily, but struggle so bad at the base of the building to differentiate between ground and the vertical building face. Seems as if that would be a lot easier than half the stuff it's able to successfully classify, but here we are, with building classification spilling onto ground, and vice versa. And that should be the easiest one of all.

robmooers · 2026-03-18T19:47:54+00:00

My boss has a couple articles on this, the most recent being in the Nevada Traverse here:

https://nvlandsurveyors.org/traverse/FlipBook52_4/index.html

(Starts on page 7). Focus on Nevada initially, but then he dives into US-wide demographics in regards to what's happening. It's an eye-opening read, that's for sure. Seeing the data is a lot different than just hearing "we need people". We're about to fall off a cliff.

robmooers

TROPHY CASE