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Usefullness of Orthos in a CAD program?


Well-Known Member
Jun 11, 2021
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Hey all...it's been a minute since I've been around. :)

I'm continuing (finally, now that it's stopped raining!) to do orthos and panos for a 35-ish acre job site. I've heard for many years that overlaying an ortho into the cad representation of a site is the bees knees; many many benefits.

I totally believe that. But. I've never seen it, and apparently my client hasn't either. (Seems odd to me, but there it is.)

I can find a plethora of videos showing me how to import an ortho, but I'm failing to find any that then go to the next step and and show the benefits of importing it.

Could somebody point me to a video? Specifically a video that shows somebody in a cad program where the ortho has been imported, and then they zoom in and check the blueprint against the ortho? Like, if a foundation has been poured, and I've created an ortho of the site, I want to show my client how useful it is to import the ortho and check to be sure the actual foundation matches the blueprint.

As you may have guessed, I know nearly nothing about construction, so I may not be using the correct vocabulary, but hopefully somebody understands what I'm saying. :)

If your client does not find value in this, I am not sure that a video will change their mind.

You are stating that you know nothing about construction but want to sell drone/construction products?

Do you know anything about local grids and have the ability to produce your ortho in said grid?

Also what are you going to tell the client when your inaccurate map is shifted? The surveyor's grid is wrong and they built in the wrong spot?
For this to work well you will need control points and/or RTK or your drone GPS derived ortho will be shifted the inaccuracy of the inaccurate GPS module of your drone. You will also need to know how to transform into a local grid when needed.

You are flat out asking for trouble trying to show that a foundation is being poured in the correct spot or is at the correct elevation or grade.
Any actionable data you give to the client that is incorrect could lead to a lawsuit.
When I was working on the UC Merced project we did a couple and the engineering staff didn't like them and seen no value.
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I applaud your desire to branch out and increase your product offering but you're absolutely creating a monster in your lap with this. Unless you have the survey skills, equipment, and most importantly the credentials you're opening yourself, your business, and your client up to a plethora of legal and ethical problems. I'd highly suggest you invest in E&O Insurance immediately if you're providing anything even remotely like that right now to a client for "locating". One mistake could ruin you and destroy your business and any associated finances (make sure they are separate get legit legal advice about this as it's a BIG DEAL.

Basically you're asking how to do and provide survey level work without being a surveyor, engineer, or construction tradesman. To put it bluntly, that's illegal and unethical in most places and even more so when you're talking about verifying construction items (foundations etc).

Keep in mind that the non-RTK drones we use have a GPS that's only accurate up to a couple meters (6ish feet) and you're looking to get centimeter level (or better) accuracy.

For reference, you can probably google "NC Drone Operator being sued by NC Survey Board". A fellow Drone Operator was merely doing and providing ORTHOS as part of his package (not for locating etc but merely for entertainment purposes) and the NC Board of Surveyors have taken him to task trying to say that he's offering Survey Materials w/o the proper credentials. It's a total BS attach IMHO. As of last month this process was still on-going and if he loses this case it's going to ruin him and set a nasty precedence in our industry.

I'd suggest you perfect your existing products and not jump into the world of survey grade offerings unless you're associated with a licensed Surveyor etc.
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Hey all; thanks for the feedback!

I didn't mean to cause any concern or mini-heart attacks; my apologies. I already knew before asking the question(s) that I'm NOT ever going to provide - or even pretend to provide - surveys, or survey-grade info to a client, and what a mess that could turn into legally. I also knew that RTK is much more accurate than GPS...and that I don't have RTK equipment. Yes, I know (nearly) nothing about construction but want to sell drone/construction products...which is why I'm asking questions and attempting to learn more. (This isn't the only place I ask questions :) ) I didn't mean to be "asking how to do and provide survey level work without being a surveyor, engineer, or construction tradesman"...though it may have sounded that way.

I simply wanted to know how useful ORTHOS are in a CAD program. If you all had boisterously responded that they are VERY useful, and "let us count the ways", then I'd have next asked you to help me understand "who" along the client chain finds them useful, and if you had suggestions about how to have a conversation with that person.

But...it looks like that's not the case. :D

So because of the lack of info that I've been able to come up with, I think I'm going to take @R.Perry 's reply as the most practical reply, and not bother trying to convince a client how useful orthos are. And since a) the only client I'm flying for at the moment hasn't specifically asked for them or found them useful, and b) orthos take the most time onsite, and c) I'm flying for free for them, I'm happy to talk to them about *not* doing any more orthos, and concentrate on the other things they've asked for (panos, cinematic video, flythrus) that I'm already doing.

Thanks again for your feedback!
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Most of what I did on the UC Merced project was supply videos, photos, and volume reports. The volume and pile reports proved to be accurate enough for the engineering staff.
I worked closely with the civil engineers and surveyors but never once attempted to step on their toes. I was merely supplying them with the information they requested.
In one of the mappings, I did of the 160-acre site, the surveyors said I was only off by twelve feet. I asked them if they would pull up their states and move them twelve feet. They didn't appreciate my humor.
One of the people that used my videos and photos the most were the inspectors and the Superintendent because they were able to visually see work progression without going out and walking the site.

As BigA said, be very careful how you represent yourself and the product that you are supplying.
I wish you the best of luck.
I am sorry if my post offended you. I gave you my opinion on it.

Using your own words "Specifically a video that shows somebody in a cad program where the ortho has been imported, and then they zoom in and check the blueprint against the ortho? Like, if a foundation has been poured, and I've created an ortho of the site, I want to show my client how useful it is to import the ortho and check to be sure the actual foundation matches the blueprint." led me to warn you against this particular thing. This is asking for trouble as what do you tell the client if it doesn't match up?

Different clients have different needs, so some may need decimated point clouds, some may need orthos, some may need DEMs.
Some might need your data for CAD, some may need it for overlays, some may need it as is. While different CAD software is getting better working with our drone data, point clouds and orthos are large in size and depending on the CAD software used can introduce problems when importing them in.
Sorry I didn't see this sooner.

Ortho in CAD is indeed very useful and I've even produced accurate surveys from them as a primary source, but a few prerequisite items to note.

I do work for a PLS, so I can call it a survey. Furthermore it's used in conjunction with traditionally collected survey data, not the sole source. If something is off about it I can determine that pretty quickly and even fix it.

I set ground control using survey grade GNSS, and correct it to the national spatial reference system.

Its important to know what you can and can't pull from it. My favorite details to use it for is parking stripes and landscaping. Those things are not critical at all if they are a little skewed, make a finished drawing look really detailed and professional when added, and are an absolute time suck for a field crew to collect on the ground.

That said, who asks for them? Usually nobody. I'm in a wierd place where I act as field crew, drone pilot and CAD operator and touch a project through most of its phases. If I'm asked to fly a site and think an ortho is going to help me, I make the call myself to set GCPs, program the flight to collect images at the necessary overlap, and process it. Engineers never ask for them, but they will brag on them when they have them.

So overall, they are a pain to make, and very situational on who uses them and how, and if you are going to pull location data from it, if you don't know what you are doing as the end user, you don't need to fool with it.

But yes, in the right situation, having a current ortho overlaid with survey data is super nice.
Bringing the orthomosaic into CAD and providing planimetrics to Surveyors, Engineers and Contractors is one of our primary deliverables. I have helped Surveyors cut their ground efforts by 60-70% in some cases. They focus on control and details that the drone can't get and we provide the topo and CAD linework for 90% of the project. One great example was a 3.5 roadway capture for the County Engineering office for them to design a roadway rebuild. One of the main benefits of using the drone is that we could document fence and physical obstruction well beyond the ROW (road property) line which became important when they were not able to receive ROW (right of entry) to the properties to collect the data on the ground.
Orthophotos let you do heads up digitizing if you are tracing out (hand digitizing) features accurately for CAD. Your drawings will be off by feet by not using them otherwise. There are some AI-based digitizing programs out there that do a good job as well, and the manual digitization technique is slowly becoming obsolete.

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