Total Noob looking for advice on Surverying

[rageagainstjg]

Hello All, I work for an engineering consulting company who has a survey crew that often surveys large areas of land to check as-built conditions for large civil projects, thank surveying 5 acres. In order to speed things up we have come to the conclusions due to the low cost of the entry point now versus 5 years ago that we should possible buy a drone and start using it along with the appropriate software to start checking these as-built areas. By "checking" these areas I mean obtaining the ground elevation points, we don't really care so much about the aerial imagery, we only care about getting ground point elevations, aerial images is only a bonus to us.

We are not expecting the finished product produced by the drone and software to be ultra specific, i.e within 1/16" of an inch or something, but would like for the finished product to be accurate within 1-2" max if possible of the actual ground elevation.

Since I am in the DJI phantom forum we of course are looking at a DJI phantom, and the specific one is the DJI phantom 3 professional. Also we see on the DJI phantom webpage we can purchase some software named Pix4dmesh.

Before I ask our basic questions I should point out that we are willing to, if it increases accuracy set control points, large X's, on the ground, with our current surveying equipment that has known elevations and X and Y position if that would help improve accuracy.

Our basic questions are these:

If we purchase a DJI phantom 3 professional and the Pix4dmesh is that all we need in order to start generating point cloud models that we could then bring into Autocad where that we could do further work with them? Or do we need to buy some type of additional software to do this?

Is buying the Pix4dmesh software a waste and we should spend our time looking somewhere else?

As a side note, I have also looked at dronedeploy.com and mapsmadeeasy.com are these things we should be looking at or should be we looking at doing the processing of making the point clouds in office?

Finally we have a yearly autodesk subscription and with it we have a piece of software named "Autodesk Recap360" is this something we should look into further as an alternative to any of the above mentioned items or is it a waste of time compared against the others.

Our end goal is to have drone and software that is capable of surveying an area and produce a point cloud that we can bring into autocad that has the ground elevations within 1-2" of their actual elevation in the field. We would love to do this all for less then $2000 and are willing to look into using a company like, mapsmadeeasy.com or dronedeploy.com as a pay for processing company if needed.

Anybody able to offer any advice? Any help out all would be appreciated.

 

[r62ewa]

You can use the P3P and Pix4DMapper, one of the outputs is a .las point cloud that you export to use in Autocad. To obtain the accuracy you require you will need to set and collect GCPs with you survey equipment. You load your GCP file into Pix4D to correct the accuracy, without GCPs you will get 5m horizontal and 10m vertical accuracy at best.

Pix4DMapper is expensive to buy to own, but they do offer a monthly rental as well. They also have extensive video tutorials on Youtube that breaks down everything you need to know.

 

[ecolumbia999]

Hi,

I think there is starting to be a lot of interest in using drones for engineering application using low cost drones. I would suggest buying the phantom 4 - it is a bit more advanced and has collision avoidance. For myself I'm still using the phantom 3 pro.

One item that you left out of your list is in order to use drones for commercial operations - including your own place of employment - you need to be licensed. The quickest and easiest way to obtain a drone license is called part 107. With some study and instruction, staff should be able to obtain a part 107 license within a month or two.

Here are three maps I did with drone deploy: This is the map I did at 100 ft: http://drdp.ly/A7T1Sn . The second map of the same place I did was initially at 100 ft but I also included oblique pictures taken at 20ft. http://drdp.ly/kRK0cu . The third map I did was at 200 ft. http://drdp.ly/zMVKqt

You can review these maps and let me know what you think. Since you are specifically concerned with the elevation maps I am concerned about how accurate the elevation maps are using this type of system. Even though all three maps are over the same acreage, the elevation maps are different using a phantom 3 + and a product like drone deploy. There might be items you can do to ensure the elevations are more accurate such as flying at a specific height or adjusting elevations later in the processing.

 

[rageagainstjg]

You can use the P3P and Pix4DMapper, one of the outputs is a .las point cloud that you export to use in Autocad. To obtain the accuracy you require you will need to set and collect GCPs with you survey equipment. You load your GCP file into Pix4D to correct the accuracy, without GCPs you will get 5m horizontal and 10m vertical accuracy at best.

Pix4DMapper is expensive to buy to own, but they do offer a monthly rental as well. They also have extensive video tutorials on Youtube that breaks down everything you need to know.

Sorry I am new, what does P3P stand for? Also I see there is a lot of different types of Pix4d software, I even see one on DJI site called pix4dmesh and it costs $500 bucks, is this able to do what I want or do I need to look at more expensive software solutions?

 

[Pharm]

P3P stands for Phantom 3 Professional.

 

[r62ewa]

It was my understanding that if you utilize an RTK GPS system to collect your GCPs then once you use this to correct your UAV GPS data you can obtain 2 cm level accuracy. From the research I've done, software systems like Pix4D state this level of accuracy is obtainable. There is also a GCP system called AeroPoints that also suggests this accuracy, as well as SenseFly's RTK eBee.

If you are interested in LiDAR for your UAV, Velodyne has the new Puck Lite that is 580 grams and requires a payload ability of 1 kg from your UAV. I know this system and many others I've listed will not get you your results for under $2000 but read the tutorial on introducing GCPs in Pix4D and watch the Youtube tutorial, seems the level of accuracy you require should be obtainable if you have RTK survey capabilities already with your company.

I use my Phantom 4 for photogrammetry and do not yet have a GCP collection system but fully expect to obtain cm level accuracy once I find the right system for my business.

 

[rageagainstjg]

It was my understanding that if you utilize an RTK GPS system to collect your GCPs then once you use this to correct your UAV GPS data you can obtain 2 cm level accuracy. From the research I've done, software systems like Pix4D state this level of accuracy is obtainable. There is also a GCP system called AeroPoints that also suggests this accuracy, as well as SenseFly's RTK eBee.

If you are interested in LiDAR for your UAV, Velodyne has the new Puck Lite that is 580 grams and requires a payload ability of 1 kg from your UAV. I know this system and many others I've listed will not get you your results for under $2000 but read the tutorial on introducing GCPs in Pix4D and watch the Youtube tutorial, seems the level of accuracy you require should be obtainable if you have RTK survey capabilities already with your company.

I use my Phantom 4 for photogrammetry and do not yet have a GCP collection system but fully expect to obtain cm level accuracy once I find the right system for my business.

I am sorry, your going to have to explain this a little bit simpler for me. In the company I work for I am basically the autocad guy, I draw maps. The guys that do the surveying I know they have some sort of Trimble GPS surveying equipment, plus I also know they have traditional survey equipment that they often use to "tie in" known points on adjacent projects so that when they send me the surveyed points they are where they are actually located in the world and at their actual elevation.
The part in your response, and it is solely based on my lack of understanding of surveying technology, is the references to RTK, so let me know if I am getting things confused,.

My understanding from what you said is if we have ground control points that are located at their true location and elevation in the world, lets say 5 in total per an acre project we can then expect with a DJI phantom 4 and the Pix4d software (the really expensive version) expect to get 2cm level accuracy?

Please let me know if this is accurate. Also as a side question would you happen to know any of the capablities of the cheaper version of the Pix4d software, the one I am talking about is the one they sale on the DJI website that costs $480 per year. Would you know anything about it mapping/putting things at their accurate location within a margin of error of 1"-2"?

 

[r62ewa]

It appears that Pix4DMesh is now called Pix4DModel, but I do see the version you refer to on the DJI site. It appears to be a version for creating 3D models for sharing on the web, along with 3D flythroughs. Pix4DMapper is their full blown version that allows you to manipulate and analyze the data. In Pix4DMapper you create the 3D model, an orthomosaic as well as a Digital Surface Model. You can also export the 3D .las file for use in other processing software, such as AutoCAD and GIS. You can also generate contours in Pix4DMapper, perform measurements and calculate volumes. It also enables you to edit your .las point cloud and mosaic for better results.

Pix4DMesh/Model is more for visualization and sharing whereas Pix4DMapper is for full blown photogrammetry.

 

[rageagainstjg]

I posted over in the Pix4d official software forum to make sure they was the same piece of software, but I believe you to be correct , with only differing names, thank you for that info and will update here if for some reason this is incorrect. Going

It appears that Pix4DMesh is now called Pix4DModel, but I do see the version you refer to on the DJI site. It appears to be a version for creating 3D models for sharing on the web, along with 3D flythroughs. Pix4DMapper is their full blown version that allows you to manipulate and analyze the data. In Pix4DMapper you create the 3D model, an orthomosaic as well as a Digital Surface Model. You can also export the 3D .las file for use in other processing software, such as AutoCAD and GIS. You can also generate contours in Pix4DMapper, perform measurements and calculate volumes. It also enables you to edit your .las point cloud and mosaic for better results.

Pix4DMesh/Model is more for visualization and sharing whereas Pix4DMapper is for full blown photogrammetry.

Thank you for this information! I do have a favor to ask, would you be willing to respond the questions I asked in my previous post about the RTK line of questioning as well as the questions about possible accuracy with the number of ground control points I mentioned as well?

 

[kitefiter]

We use Trimble RTK GPS to set GCP on all our projects. When we fly the project at less than 150' we are getting consistent accuracy of less than 0.1' Pix4D states accuracy of 1.5 times the GSD.
Here is the GCP table from a recent project flown at 200' on a 25 acre parcel.

 

[kitefiter]

I just went back and reread your first post. We can fly the project and process it with Pix4d. The biggest hurdle has been getting to a "pretty" looking surface with contours. The huge number of points has two problems. The point density is too close for smooth contours so figuring out the sampling rate so the contours don't look like lightning bolts is tricky. And two, vegetation. Trees, grass, cars, structures etc. are very hard to clean up. Pix4d does a fair job but there can still be a lot of operator time to remove the ghost clutter and get the surface smooth. Recap is supposed to do some decimation and filtering but we have not been to successful with it. Civil3d can sample and smooth but this loses the accuracy that you are looking for. We are looking at TOPODOT but this solution is another $5400. This is why the topography standard is that 90% of the map is within 1/2 of the contour interval. I think that drones and modern computers and software will change the industry but it is a work in progress.

 

[rageagainstjg]

kitefiter, you information has been great! Have you ever looked at any of the online services such as mapsmadeeasy.com specifically?

I have to additional questions as well, if you would be willing to answer them for me.
1. I have never used Pix4d software, does the pix4d software classify the points for you at any point? Such as water, building, bare earth?
2. If it doesn't classify them for you what exactly do you get out of pix4d? Is it just a point cloud of all items captured in the picture and then you start working with the point cloud and try to remove things, cars etc, to make a finished product manually?

 

[kitefiter]

Pix4d does a simplified classification into objects, terrain, deleted, and unclassified. It also lets you define your own class. The operator has control of dimension limits to help in the classification. I found that there is almost always some noise. It also has a good editing tool so you can go back and isolate an area and move it to a working class. Then I turn off the other classes and turn the working class 90d around the zenith. Now I can remove the noise and leave the surface I want. Then I move the good points back to the terrain classification. This works pretty good for cars, trees, poles, etc. But Pix4d is not great at small bushes with limited vegetation and with grass. But I have not found any other software that is great at this either. Global Mapper is better at classification and we are still testing TOPODOT.

 

[kitefiter]

I found the output from Mapsmadeeasy to be fuzzy in some areas. At the time I tried it, it did not do GCP and the vertical accuracy was definitely not good enough the projects I am working on. Most of our work is for topography maps for either design or volumes.

 

[benjie217]

I have been using PIX4D mapper pro, with Ground control point set or tied in with RTK, and have gotten real good scale ability for topo checks and 0.05' to 0.10' on hard surfaces short grassy area, it dose have a problem with brush and tall grass, these can be removed using the ray editor, you can also set in options a grid pattern which will space out the point cloud points to match a grid, reducing the number of points to 100 per square meter (or user setting) which will generate smoother contours. I am still testing and learning the software options (PIX4D mapper pro)

PLS and Remote pilot certified

 

[asisel]

I have been using PIX4D mapper pro, with Ground control point set or tied in with RTK, and have gotten real good scale ability for topo checks and 0.05' to 0.10' on hard surfaces short grassy area, it dose have a problem with brush and tall grass, these can be removed using the ray editor, you can also set in options a grid pattern which will space out the point cloud points to match a grid, reducing the number of points to 100 per square meter (or user setting) which will generate smoother contours. I am still testing and learning the software options (PIX4D mapper pro)

PLS and Remote pilot certified

benjie217 how do you take into account topography while surveying a large area that is also "hilly"? In my state, you need a PE or PLS to do surveying (measurements, boundaries, etc.), but just doing straight imagery I think one is OK. As long as it stays in-house and is not for public use. Do you face the same issues where you are at?

Thanks!

 

[Richard R]

You can use the P3P and Pix4DMapper, one of the outputs is a .las point cloud that you export to use in Autocad. To obtain the accuracy you require you will need to set and collect GCPs with you survey equipment. You load your GCP file into Pix4D to correct the accuracy, without GCPs you will get 5m horizontal and 10m vertical accuracy at best.

Pix4DMapper is expensive to buy to own, but they do offer a monthly rental as well. They also have extensive video tutorials on Youtube that breaks down everything you need to know.

You can do the same thing with Maps Made Easy. GCPs can be identified in pictures with surveyed positions entered. Even without GCPs, the relative accuracy between points is pretty good (on the order of a few centimeters). It's when you need to know where the points are on the world map that you need surveyed points. MME outputs include ortho, DEM and 3D (.las and .xyz) files. Their web page currently has info on using the DEM file with another free program to generate contours. Recently mapped the local soccer park. Over 50 acres, took about 8 min. I flew at near 400 ft AGL to keep the number of points below 250 which allows me to get the data processed free! Results were 1.9 in pixels. Could easily determine the slopes in the fields, drainage channels and the shapes of the foot bridges over the channels.

 

[Mromansea]

I found the output from Mapsmadeeasy to be fuzzy in some areas. At the time I tried it, it did not do GCP and the vertical accuracy was definitely not good enough the projects I am working on. Most of our work is for topography maps for either design or volumes.

Kitefliter where are you based out of? I'd like to talk to you about your work. We may have some business for you.

 

[Mromansea]

I found the output from Mapsmadeeasy to be fuzzy in some areas. At the time I tried it, it did not do GCP and the vertical accuracy was definitely not good enough the projects I am working on. Most of our work is for topography maps for either design or volumes.

The contour following function is great - but I agree the imagery is less than ideal. The app itself is also buggy. I'm actually looking for another contour following application as we do a fair amount of work in hilly terrain.