Wednesday, March 26, 2014

Point Cloud beginer tips

A project I am working on at the moment is a complex Hotel that is requiring a complete refurb on an extremely tight deadline.

This project is located overseas from my office here and I have been collating and managing the team to capture the existing conditions, we are modeling the entire structure in Revit.

To speed the process we have been getting the whole building point cloud scanned, and so whilst I have dabbled in LiDAR and point clouds on a few projects this is my first project in which we are dealing with them on a day to day basis, and a large volume of data aswell.

So to begin with I have been using ReCAP, which is pretty simple to use view, cut/crop and then export the clouds for various uses.

However before that I needed the data in a usable format, due to the surveyor initially providing us raw data which was useless, I managed to find a text file that told me the make of scanner Leica and used that to determine what data the default technology can export, and asked for that from our surveyor.

To date we have been asking and dealing with pts files, however I have since been told (Thanks Brett from Autodesk) that ptg is a better format as it's ascii readable and therefore there are less translations woe's so in future this is the format we will be requesting.

Our second issue has been converting the exported files to the Autodesk recap/scan files, as these files can be anywhere from a couple of gig to 150gb this can take a long time, the first couple of scans were being copied across to our server and then converted with the copy/conversion process taking up to a day for the larger scans.

We have since setup a computer in the project office and I remote in to that, as the conversion from the point file to Autodesk scan file can drop the size of a file by as much as 70%. We then copy the converted file across enabling our team instant access to the new data once it has been copied. We did have an issue with the graphics card not being able to run the right version of OpenGL in a remote desktop session, so in this case we needed another computer in order to get access to ReCAP.

The first thing I recommend when using recap is to set your temporary folder to somewhere where you have ALOT of hdd space. Our conversions of large scans say for instance a 45gb required an additional 65gb of conversion space to convert the file to the Autodesk format.

Our office standard is small SSD C drives and with all the other software I only have about 40gb spare at the moment so change this in your settings.

I will post some more key things in the future, but the major ones I have learned are;
Change your temporary folder locations for conversion
If you need to move cloud file between offices, convert them first to lower transfer times.
Ask for ptg files for readability
Using Remote Desktop services may be an issue if your card doesn't support at least OpenGL 3.1 for remote services.

Otherwise I have had no issues with locations or grid co-ordinates when loading files into Revit, I will provide additional updates on tips & tricks.

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