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Import Topcon Civil tp3 file

If you are given a Topcon TP3 then it is possible to import the data into Ezigrade. At present we can't import a tp3 file directly but we have an easy workaround. All the Topcon Civil file formats are propriatery files. As such they don't have a published format. The tp3 file is the native file for 3D-Office and includes all the control points, line work and surfaces. As such it is reasonably complicated. However Topcon also has a number of subfiles: GC3 which contains the control points, LN3 which contains linework and TN3 files which contain surfaces. These files are much easier to understand as they only contain the particular type of entity.
The first thing to do before importing the data into Ezigrade is to view the tp3 file in #D-Office to have an idea of what we are trying to import.
This file is an example from a client. They want to import it and ultimately create a Trimble FL2 file. Opening in Topcon 3D-Office shows us the following:
In this example we want to resend the data out to another machine control file. So we only really want to include those features that you would want the operator to see in the field. In this example we have a background grid and other things we don't want. In 3D-Office click on Project -> Layer Selection and Management. As a minimum we want to turn off the grid. But look for other layers as well. In this example we have two separate triangle surfaces. I would inspect them. In this case we have an existing picked up surface and a design surface. If we just display the design surface we can see this:
The next thing to check is what units we are using. ie Meters, feet or survey feet. We also want to be able to georeference the data. So the data already needs to be in UTM or State Plane system etc. In 3D-Office click on Project -> Control Points. In this example we see that the points have lat/longs associated with them which we can use. However I also see that the coordinates look like State Plane to me. As a check I used the lat/long displayed to look up the area in Google Earth and I can see that we may be using State Plane - Georgia West. I will explain how to check this later.
So in 3D-Office we want to create a GC3 file, a LN3 file and two TN3 files.To create the GC3 goto Project -> Export Control Points -> To 3D Control File. To create the LN3 you first select the appropriate strings and then Linework -> Export Selected Linework. For the triangles you need to make each surface the active one and then  Tin -> Export Active Surface.
We now need to open Ezigrade, and from the File -> New menu create an empty job. The next step is to make sure the units are set correctly in Ezigrade. Click on the File menu and make sure the correct units are set. In this case we want US Survey Feet.
Now go Import -> GC3 and browse to the GC3 file previously created from 3D-Office. Click OK and the control points are imported. We get this:
You will see the small cross's. At present we need to tell Ezigrade these are going to be control points. If you look at the screen shot above, look towards the bottom left and you will see the icon with the red cross's. These list the points in the job. Click on this. Be aware that you can drag the edge of the view to make it wider. In the view shown I have put in a code for MB fior the masterbench and a list of benchmarks.
If you go back into the view and redraw you have:
At this point I would be checking that my guess for the geoid used was correct. To do this I will export the control points to Google Earth.
Obviously your data will be different and you may not be using State Plane. In this case don't preset this. Now click on Export -> Google Earth and only export the control points
In this case my guess was correct so we can set it for the job. Don't do this if we don't know the geoid yet.
First click on File -> Geoid and I have set as follows:
We now want to import the linework. Click on Import -> LN3 (Topcon) and the linework is brought in:
In this job we have two triangle surfaces to import. Doing the picked up surface first:
and OK and we get the surface. It is worthwhile creating contours to make sure it looks OK:
Repeat for the design surface. Type in Design instead of Natural.
We now have the data imported into Ezigrade from Topcon TP3 file.
If you haven't been able to ascertain the Geoid system used and you need it georeferenced then look at the Tools -> Local Transform menu item. For this to work the TP3 file needs some lat and longs set for some of the control points.
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