Recap Survey Points - How do you align a pointcloud?

[JasonMeshach]

So I have an 18 scan room that when completed, I want it to align to a specific set of points in an AutoCAD file...  so the final pointcloud rotates and aligns to those points.

As a test, I started with only 2 of the 18 scans to try to understand using survey points.  I can see during the registration process of comparing two scans that the left window you can click a point and create a survey point by clicking the little arrow under the colored circle.  I've created (2) survey points in that scan window naming them CP1 and CP2 and within each of those points I've entered the X,Y,Z values to the corresponding points in AutoCAD (after converting the ft-inches units in CAD to meters for Recap).  After creating the two survey points, I clicked the 3 green,blue,red points in each scan and it did it's thing and aligned the two scans.  However, after it is done and I click to index the scans...  its like it completely ignored the survey points and never aligned the final pointcloud to those survey points. 

What am I missing here with regards to survey points?  How may survey points do you need to be using?  Should I have survey points in more than 1 of the scans?  How do I accomplish lining my pointcloud up to my AutoCAD file?  Do I need to export the pointcloud to a certain format to get the survey points to kick in?

Also, I noticed that instead of naming the survey point I could import a txt file list.  What is the format for that and should I use that over manually creating them?  How does importing survey points work?

Thanks for any help.

[cheliotes · Accepted solution]

Jason, you can import the control file as a metric x,y,z .txt (Tab delimited). Once you have chosen the control file in the survey point drop down, all points in the text file will show up in a list. You must have a minimum of 3 control points defined before you see any RMS quality values. Hope this helps.

[JasonMeshach]

Okay so 3 control points.. that got me going down the right path.  Thank you very much for that information. I can choose 3 points and name them enter the x,y,z values and get my pointcloud closer to where I need it, but I'm still not perfect as now my pointcloud is not nice and flat anymore.  Will continue to work at this more.

Going back to the importing the control file. Each line in the txt file is simply 3 numbers seperated by a number value right?

Example:
200,100,0
100,2,0

So I made up a text file of 3 points and when I "upload survey points (*txt)" during the registration process it doesn't appear to do anything. It would make more sense to me that each line in the import file would have some sort of name associated with each xyz value and the list of names would pop up in the drop down list to choose from to assign to that point. Right now when I open my testpts.txt file it doesn't do anything. What am I missing?

[cheliotes · Accepted solution]

Jason, keep in mind that the control points will only work if they are geometrically accurate (the distances and directions between control points in CAD are the same as they are in the point cloud). This method only works if the control is created before assigning control points in Recap (I know, hard to explain, hard to follow). One way I can think of to fake it would be as follows (start with just a single scan):

• import a scan into Recap
• Hover over some easily recognizable points and write down the coordinates shown at the bottom left
• Create an Excel spread sheet with the coordinates (Point#, X, Y, Z) like this:

• Then, save as a txt tab delimited file

This is the control file that you import when prompted in the control point dialogue.

So, you don't actually name the control points in Recap, you simply pick them form the control file.

I know it's a bit of a wrestling match at first, but pretty easy after you get it figured.

Good lluck.

[JasonMeshach]

Thank you very much for this information. Now I understand what they're looking for in the control file and how it's supposed to be formatted. Hopefully you won't mind if I have a few more questions in the near future. 😉

[zachc1]

Cheliotes, I have a few questions that you may be able to help me out with in regards to your response.

First question, are the coordinates in the txt file the desired location of the survey points in ACAD, or their current location in ReCap?

Next question, can the coordinates be entered into the txt file in ft & in format?

Last question,  Where do you access the control point dialogue?

Thank you in advance for any assistance you may give me.

[cheliotes]

Hi zach,

I will answer as best I can.

1. The coordinates in the text file represent the coordinate where you want the point to end up (the ACAD points). The coordinates in Recap are arbitrary based on the center of the first scan being 0,0. If you want to move the Recap point cloud to a set of coordinates, you have to provide the coordinate that the targets should move to. Hope that makes sense.

2. The coordinates must be converted to meters. The display units in Recap can be modified after indexing, but the import/export units from Recap will always be meters.

The control point dialogue will show up at the bottom of the screen during the registration process:

Once you have selected the target from the scan, you will be prompted to create a Survey Point. You must upload the control file from the drop-down list, then pick the correponding point from the list.

I hope this helps. Feel free to message back if you are still having trouble.

Chris

[zachc1]

Okay, I think I understand it now. I have already done the targetless registration using ReCap Pro for the project that I am trying to align, so I am going to see if I can do this post registration. I can't believe we can only use meters for the control points. AutoDesk added feet & inch as an available unit for the point cloud. Maybe they will add it for the control points in a hotfix. Thank you for your help.

[cheliotes]

I too hope the add the ability to import control files with imperial units. I missed today's webinar regarding the Recap version 2.0 release today. Perhaps this functionality will be part of the release.

Also, if you are having difficulty getting the point cloud to move to your coordinate system, try removing the last scan from the registration, adding the control points, then re-registering the last scan. Good luck!

[PC2C]

Hi Cheliotes,

is the only way to assign a target (refence sphere or checker coard) using imported reference points by using the drop down menue? We work usally with more then 100 refence points and it's really a difficult way doing it.

Thanks,

PointCloud2CAD

[richiee]

I'll verify it to be sure, but I believe that it should narrow the list to the survey points in that general vacinity of the project. What version are you running?

[I.Thiele]

Recap Ultimate 2016

[zachc1]

I have found that you can also just enter the coordinates in the x, y, & z fields after selecting to make the point a survey point and naming it. It still has to be in meters though.

[cbrundidge]

What's the difference in entering survey coordinates in the two below screen shots?  The first image is what you get when you first click the target icon.  The second image is what you get when you click on the "make survey point" on the first image.  What does one do over the other?

When I bring in that text file on the second image it populates the lower row(xyz) with the survey coordinates and leaves the upper row unchanged.  Are the second row of numbers still in meters?

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[thebearjed]

I have the same question as  cbrundidge. can someone explain these 2 options?

[admon]

Hey Guys! I have some questions regarding this topic.

1. The values I add to Survey Points are the actual values I have from XYZ or the difference from the values the Survey Point has from default VS the actual values?

2. I tried both scenarios and I get my point cloud somehow close to the XYZ values I want it to be, but not close at all, and also the whole point cloud shows rotated.

Why is this? Please help! Can't find any solution.

[thebearjed]

Has anyone had success with aligning Point Clouds in Recap without Total Station data?

currently we are scanning the area using a BLK360, transfering the data to our desktops, and then trying to set the X, Y, Z coordinates to our local Plant coordinates using the Make Survey Point feature in Recap. Unfortunately we have had no success with the last step.

we have tried to use the steps as defined here...

https://knowledge.autodesk.com/support/recap/troubleshooting/caas/sfdcarticles/sfdcarticles/How-to-l...

and here...

https://knowledge.autodesk.com/support/recap/troubleshooting/caas/sfdcarticles/sfdcarticles/How-to-c...

again, without any success.

[thebearjed]

apparently you have to change the X,Y,Z coordinates before you index the scans.

[stephenGSKHY]

I have the same issue. The survey points are entered via .txt file, and the targets are all assigned to the survey points, but they don't align to survey points after registration.

[tim.vetter]

I have the same issue.  "Has anyone had success with aligning Point Clouds in Recap without Total Station data?  I agree with "thebearjed" that the two Autodesk workflows provided lacks functionality for what the customers need.  The problem with the first Autodesk link is that this workflow only applies to registered projects which are NOT already aligned.  If you choose to level your point cloud using this workflow then you can NOT perform another alignment in the X,Y direction.

I added the following Idea to hopefully address this functionality issue:

https://forums.autodesk.com/t5/recap-ideas/make-survey-points-with-1-2-or-all-3-axis-values/idi-p/73...

I hope to see this survey point idea added ASAP.