Gnss / GPS system points issue

SketchUp Pro
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1

Hi.

I have recently acquired a topcon gps system, which I use on site to collect some data. Within the system (Magnet field), I can create lines, points, offsets, angles, basically I can create a floor plan from scratch within the data logger, but it is a pain and slow.
I got sketchup pro with the plan of importing the (Accurate to within 5mm) points I take, and editing them to create my design or space (foundations, shed bases, patios, walls, pipes etc) and then export back to my gps system so I can layout a site quickly and efficiently.

My issue is this, when I create my plans from within the system, it works perfectly. I am in Northern Ireland. When I import the points to sketchup and try edit, a lot of the times the points cloud disappears on me when I’m panning around and moving. However the main thing that bugs me is when I geolocate this, or add a location, my points are either near Norway, or else near France. I have tried 3 things ;
I have added the location first, imported my points and moved them to the geolocation of where they are supposed to be, and exported.
I have created a new file, imported my points and just directly exported them again.
I have imported, added location, and kept points where they are, and exported.

Every time I export and open the file on my gps, I am about 1500km away, in random directions, sometimes north, sometimes south. This is no use to my gps system as I got it to make my life easier, not more stressful!

I have been contacting topcon support, they suggested changing the import units from meters to mm, and everything else but I tried all this and nothing helped. I have contacted sketchup support but they aren’t fully sure and have told me to try post here because maybe (Hopefully) someone will have experience of this!

I thank you in advance, and if anyone wants some screengrabs posted, let me know and I will get them to you within a day or so.

Thank you, Happy modelling!

:smiley:

2

The Add Location feature does not geolocate your design from a true survey / geospatial perspective… it’s primary use is to provide the image and basic terrain data in the needed location for the design and to help position SketchUp’s shadows correctly.

That being said, there maybe a few workarounds to get your model positioned correctly.

What are you using to import your points?
Can you share the point file so we can dig into your issue further?
What format are you exporting out to? What “gps” software are you using to visualize your design?

Cheers
ChrisD

1 Like
3

Hey Chris.

So I am using topcons hiper cr system, it’s accurate to about 6mm, and it runs on a software called magnet field.

I use magnet field on site to manipulate points and draw basic things but sketchup is much more simple.

I collect the data points with magnet field and export them in a .dwg format to my google drive, then I import to sketchup. My problem is if I export the file from sketchup at all, that’s when it becomes faulted. I can edit the file in sketchup, however the location is really far from the origin point and my points keep disappearing with the slightest movement.

I will add the files here, so you can see a couple of them and see what I mean. As it is all new to me I’m keeping things simple, so the points in the main file in question are just 3 points as a straight reference line, which I am building foundations off.

Brendan devlin shed base.dwg (12.5 KB)

Brendan Devlin Shed Autocad Base.dwg (439.0 KB)

so file 1 is the raw data, file 2 is the edited and exported data. It also may be a flaw in the system of both sketchup and magnet field, not entirely sure.

I appreciate you taking the time to look into this,

Thanks,

Thomas

4

When you are setting up the using the Topcon Magnet Feld job, are you designating a particular Projected coordinates system.

The points are coming into SketchUP far from the origin because it is respecting the origin of the CRS these points are using for reference.

You need to bring your reference points closer to the SketchUp origin for easier modeling (without rotating). > Create your geometry > send it back to it’s proper location far from the origin.

Workflow Option - Use of the Trimble Sitevision Extension
The Sitevision extension is meant to be used to relocate SketchUp 3D designs for visualization within Trimble’s geospatial Sitevision solution. We are going to use it for relocating your design for use within Magnet Field.

  1. Record the coordinates of a point that will be positioned at the SU origin
  • Using the Text Notation tool, you can derive the coordinates from a edge vertex in SketchUp so draw an edge between the construction points.
  1. Bring the point set to the SketchUp origin
  2. If needed, reposition the modeling axis.
  3. Use the Sitevision extension to register the coordinates of the construction point at SketchUp origin.
  4. When the design is ready, use the Sitevision extension to create a new Skp file that contains your design at its “original” location
  5. Export your DXF/DWG from the new sitevision model.

Here is a video showing the sitevision workflow.

Here is the resulting DWG from the sitevision model
foundation_SiteVision.dwg (273.5 KB)

Let us know if this works for you. There are other similar workflows that dont require an extension we can try but this one seemed to be the most direct option

NOTE: From within Magnet Field, you might need to assign your projects CRS to the imported dwg data in order for it to be positioned properly.

  • ChrisD
3 Likes
5

Ok, so I had a look at this and uploaded the file into my gps system, and it worked perfectly!

I’m very happy about this. But now to figure out how to make sense of the process you have used, I will study what you’ve posted and check the workflow also, and then I will practice and see if its something I can duplicate, and test it with a few different jobs and see if I can get it working!

I will keep you posted on my progress,

Thanks again Chris,

Thomas

1 Like
6

Hi again.

I have downloaded the site vision extension and tried to replicate what you have been showing me in the workflow however I am experiencing some issues.

  1. When I import a drawing, the first thing that happens is that all my points seem to be grouped, therefore I cannot get the origin point. However when I explode the group, I can get a point but when I use the text function, only the file name shows up and I do not get co-ordinates showing up. I have researched and found that the tape measure shows these when hovering, but there is no method to record them except pen and paper and the dialogue box that appears only lasts for a couple of seconds and I have to recover several times to record them.

  2. When I do record the coordinates and move the drawing to the origin, I use site vision to plug in the old coordinates, but nothing happens.

  3. When I try export using site vision, my file won’t export or save, and I have no option to select a format in which to export or save. I have tried just saving a reopening but it won’t even save as a .skp file for me so I can’t find it when I try open a new file.

  4. I found some form of the file but when opened the file is still at sketchup origin and coordinates are 0000000000, however the site vision extension shows the coordinates the same as the ones I have typed in.

Would you have any idea on what I’m doing wrong? I have tried my best to follow your process step by step.

I will attach the new file I’m trying to use here, so you can have a look at it.

Training file 9th December.dwg (22.0 KB)

I hope its an easy fix!

Thank you,

Thomas

7

First, it is worth mentioning that since your imported cad linework is far from the origin, you will probably see some strange visual behavior (shaking, jittering) while you navigate around geometry. This why we are brining the geometry closer to the origin. For a better understanding of this issue, here is on old video talking more about it and ways to correct it.

1. When I import a drawing, the first thing that happens is that all my points seem to be grouped, therefore I cannot get the origin point. However when I explode the group, I can get a point but when I use the text function, only the file name shows up and I do not get co-ordinates showing up. I have researched and found that the tape measure shows these when hovering, but there is no method to record them except pen and paper and the dialogue box that appears only lasts for a couple of seconds and I have to recover several times to record them.

  • The text tool only displays the coordinates of vertices. It will not work on construction points (we need to get this corrected. I will submit ticket).
    All you need to do is draw a vertical line from the construction point and then use the Text tool on the line vertex

2. When I do record the coordinates and move the drawing to the origin, I use site vision to plug in the old coordinates, but nothing happens.

  • Recording the coordinates in Sitevision is for the export stage. The act of registering the coordinates will not modify the geometry location. You have to do this manually (see in video)

3. When I try export using site vision, my file won’t export or save, and I have no option to select a format in which to export or save. I have tried just saving a reopening but it won’t even save as a .skp file for me so I can’t find it when I try open a new file.

  • There is one issue with the extension I failed to mention that I think you came across. You have to SAVE your model first before you use the Export feature of the Sitevision extension. The model has to be saved in order for the extension to know the where to save its version of the skp.
    ie… Save your model first and the Export feature should work fine.
  • When registering your coordinates in the Sitevision extension, there is an Units option. This will tell SV extension what unit to use when moving the geometry back to the registered coordinate. The export results in a new SKP file. This new SKP is what you will use to generate your cad file.

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Video Demo 2
Below is a recording of the import and relocation of your Training file 9th December.dwg (22.0 KB)
Note that before I relocate it to the origin, I am going to relocate the cad component axis first. This is to help with the visual display issues talked about in the video above. I will also relocate the geometry by typing the absolute coordinates of 0,0,0 inside [ ] (brackets). See video above.

Here is the resulting skp
Training file at ORIGIN.skp (46.4 KB)

ChrisD