Road survey

Discuss all Construction & Architecture related issues here.
Post Reply
james_michel
I have made <0 posts
I have made <0 posts
Posts: 5
Joined: Thu Apr 14, 2016 9:14 am
Full Name: james
Company Details: geobe
Company Position Title: draw
Country: france
Linkedin Profile: No

Road survey

Post by james_michel » Mon Jul 04, 2016 2:13 pm

hi,

( i apologize for my english)

We have laserscan FARO x130, and our customer don't understand how and works scanning, and he say scanner FARO don't make survey road :shock:

he say : "Au-delà de cela, les trois coupes fournies présentent encore des écarts de précision supérieurs à 5mm et pouvant ponctuellement aller à 9mm. Concrètement avec la méthode utilisée et le matériel utilisé, on ne pourra pas atteindre de précision plus fine."

i think he make an error whith Distance and Noise Z (5mm to 9mm)
Image
it' me or our customer make a confusion?

if i want analyse a road after and before (horizontal drilling)
i use geomagic for drawing mesh of road before drilling , and after i use cloudcompare or geomagic and i see analysis

what it's better workflow? and how to explain our customer ?

With The Scanner FARO x130 How many mm at 50m (3mm or more?)

fgvm
I have made 10-20 posts
I have made 10-20 posts
Posts: 19
Joined: Thu Aug 25, 2011 8:47 pm
Full Name: fgvm
Company Details: VM Ingenieros Consultores.
Company Position Title: Gerente
Country: Guatemala
Skype Name: ffvela
Linkedin Profile: Yes
Contact:

Re: Road survey

Post by fgvm » Tue Jul 12, 2016 7:02 pm

James, sorry for the delay.
I would recommend that you do your job in two phases.
1. Define a Survey Control Network. This network should complied with your country surveying standards for this kind of project. Please use a differential level method for determine your network elevations.
2. Tie your scanning to this Survey Control Network.

No regarding your methodology for scanning, there are a few concepts that you have to understand very clearly.
Angle of Incidence: It is the angle formed between the surface your are measureing and the Laser from the scan.
You should try to limit this value. You shoud limit the distance of your scanning or try to elevate you scanner to reduce you angle of incidence.
Accuracy: The values that comes with the equipment (surveying, scanner, TS), are estimated in controled environments. Under very specifics conditions for example. For example Normal Incidence, reflectivity, temperature, ligth conditions ,etc.
Type of Surface: Very dark surfaces like Asphalt may not work always rigth with phase base scanners.

I think that if you manage to control this variables, you will have a good and consistent pointcloud to do your analysis.

CALTRANS, the Departament of Transportantion of California, USA. Have a documente where they established a methodology to do this type of work, with laser scaners.
http://www.dot.ca.gov/hq/row/landsurvey ... urveys.pdf

CERTAINTY 3D, have a very specific software to do what you are trying to do. Incluiding a automatic tripod for your vehicule. Look for them in the web. They also have an excellent paper on establishing requirements and extracting metrics from your pointclouds.
http://www.certainty3d.com/pdf/technote ... ics_QB.pdf

Hope this helps!!! :D :D :D

Graham
V.I.P Member
V.I.P Member
Posts: 153
Joined: Mon Apr 27, 2009 3:38 pm
Full Name: GrahamM
Company Details: AVEVA
Company Position Title: Software Engineer

Re: Road survey

Post by Graham » Wed Jul 13, 2016 12:08 pm

It is great to see specifications like these, defining the possible errors in capturing the data and what is considered acceptable. The question I have is though is how common are such documents and are they even referred to by those in the commissioning organisation.

Potentially with the commoditisation of laser surveys there is the danger that someone commissioning a survey will have no idea what to ask for or understand what they are receiving. The last time I checked surveys were still not cheap, and clients were expecting even more value add using them than previously.

This is just an observation as laser surveys are being used more and more.

james_michel
I have made <0 posts
I have made <0 posts
Posts: 5
Joined: Thu Apr 14, 2016 9:14 am
Full Name: james
Company Details: geobe
Company Position Title: draw
Country: france
Linkedin Profile: No

Re: Road survey

Post by james_michel » Wed Jul 13, 2016 12:33 pm

ok, thank for reply

Post Reply

Return to “Construction & Architecture”