Converting GEO TIFFs to DXF Files for CAD

[jmason702]

Does anyone have experience doing this in QGIS or a simple converter tool?

I tried in QGIS but keeps failing...

I'm looking at Carlson Photo and Carlson Survey. The Survey one is out of my budget and not my field, The Carlson Photo Capture, I'm looking to see if it can export your Ortho Photos in a DFX format.

Any input would be helpful

 

[jmason702]

Is Ken Booth on here? @kenbooth
Is the V1 going to get the new mapping firmware before they stop supporting it?
I hope so! If I can get that I would be happy, with no more support for V1

 

[Dave Pitman]

Does anyone have experience doing this in QGIS or a simple converter tool?

I tried in QGIS but keeps failing...

I'm looking at Carlson Photo and Carlson Survey. The Survey one is out of my budget and not my field, The Carlson Photo Capture, I'm looking to see if it can export your Ortho Photos in a DFX format.

Any input would be helpful

Are you trying to convert a raster surface to vector?

 

[jmason702]

Not sure, I'm trying to take a geo tiff and convert it to a DXF so it can work directly in AutoCAD

 

[Dave Pitman]

A dxf is a vector file that consists of points and/or lines. The DEM that you are used to is a geo.tif which is a raster file where xyz is represented in pixels. Typically, if your goal is to deliver a vector surface for CAD, you would start with a mesh (3d model) and not a geo.tif. The problem is that if you go from a 3d model to .dxf vector, the file will be prohibitively big for use in CAD. So, you have to reduce the complexity of the mesh first by decimating it one way or another.

If you have a client that wants a vector representation of the surface, you need to find out exactly what they expect. Many don't really know what they expect when going from traditional surveyed points to a surface derived from a point cloud. If they try an load up a .dxf that is a direct product of your 3d model, their computer will likely choke on it. If they know what they want or expect, that's great. You can work toward that. But many don't know and it becomes a trial and error type thing. Been down that road in the past.

Anyway, in Metashape you can decimate a mesh (model) and deliver in .dxf Global Mapper is another app that can work between raster / model / and vector. But I would advise you figure out exactly what you are trying to deliver before throwing $$ at additional software.

 

[jmason702]

Thank you, this info helps ALOT

 

[Rusty_SWO]

The functionality you seek is in AutoCAD Civil 3D, and if you've got base AutoCAD on subscription then you also have all the verticals of it.

You want to start with a point cloud out of Recap, then put that into Civil 3D and you can convert it to a usable surface model there, which you can then send to Revit or whatever other modeling package you use.

 

[Dave Pitman]

He doesn't want to design himself. Just to supply topography to someone who does. Autodesk is total overkill for that purpose.

 

[Rusty_SWO]

He doesn't want to design himself. Just to supply topography to someone who does. Autodesk is total overkill for that purpose.

Well, that's an interesting point you make, but if you want to do professional work it's not really overkill to have the right tools for the job. Or, alternatively, for project types that are less common, to make friends who can occasionally subcontract for you.

 

[jmason702]

Well, that's an interesting point you make, but if you want to do professional work it's not really overkill to have the right tools for the job. Or, alternatively, for project types that are less common, to make friends who can occasionally subcontract for you.

I agree, but not when every penny comes out of my pocket for this endless software needs...

 

[jahalnon]

I use the Carlson products, Photo Capture, Point Cloud Advanced and Survey with Icad engine. The workflow from point cloud .las file to cad is where the real works begins. Photo Capture has some basic tracing tools to create 2d polylines. Point Cloud has extraction utilities that are still a work in progress. It can extract breaklines on slopes reasonably well but does not work so well on curb lines. It does create an exportable dxf of contours.

So I open or start a drawing in Survey, import the geo tif file from Photo Capture, pick off 3d points and 3d ploylines in Point Cloud, which are drawn in Survey, then refine the polylines in cad from the geotiff. It is a lot of work that requires all the software. Of course we supplement with a lot of traditional field survey data for the bulk of the cad file. Creating a tin and contours is better handled in the Cad environment. The contours look better than the point cloud version. A good geotiff of the site is indispensable! That has been the best part of the drone to cad workflow. I put the geotiff on a separate cad layer and thaw/freeze it whenever I need to see something better or fill in as I go along doing cad work. Picking off parking lines, stripes and traffic pattern paint has been a game changer with the geotiff. Most of this we don't need 3d for the model so is all done as pure planimetric detail with 0 elevation.

The Carlson icad version of Survey is far cheaper than the Auto cad standalone version. I recently switched from the acad version to the icad version. Not missing much from switch.

 

[yarrr]

Does anyone have experience doing this in QGIS or a simple converter tool?

I tried in QGIS but keeps failing...

I'm looking at Carlson Photo and Carlson Survey. The Survey one is out of my budget and not my field, The Carlson Photo Capture, I'm looking to see if it can export your Ortho Photos in a DFX format.

Any input would be helpful

Looks like you're sorting through what is needed, and great input from others above.

I'll add that contour creation in Pix4d is outstanding. I suspect this is what your client actually wants/needs- and Pix4d creates DXF contours from the DSM or DTM. I've tried many different QGIS plugins, ArcGIS, Carlson, and Autocad- and the contours from Pix4d are reliably the simplest to create, visually look the best, and are a manageable level of detail/size.

I use Autocad Civil3d on a daily basis. Integrating UAV data is a non-stop headache. As Rusty mentioned, point clouds work fairly well, and this is likely the direction things will continue to go in. Frequently however, I create my CAD surface from the Pix4d contours.

 

[jahalnon]

This may be an aside to your original question but this guy shows a speeded up workflow of pointcloud to cad using this open source sofftware. You may want to look at it to see if that is something that would help.
But the video demonstrates the current process for turning dots into lines.

 

[Dave Pitman]

Well, that's an interesting point you make, but if you want to do professional work it's not really overkill to have the right tools for the job.

Sure. But the first step is to determine what the task actually is in order to select a proper tool. That is what real professionals do.

 

[jmason702]

Sure. But the first step is to determine what the task actually is in order to select a proper tool. That is what real professionals do.

I have been doing some mapping for a CAD department for Mechanical design, and they don't know how to use or convert the files to work in Navis, Revit, etc. So I am trying to give them a file type they can work with... I know it seems pretty sad a CAD department can't figure it out. I'm a data collector, nothing more...

 

[jmason702]

This may be an aside to your original question but this guy shows a speeded up workflow of pointcloud to cad using this open source sofftware. You may want to look at it to see if that is something that would help.
But the video demonstrates the current process for turning dots into lines.

THANK YOU

 

[jmason702]

For example, I'm flying a huge rooftop of a building, where many pipes and duct work, and AHUs will be installed. I want to, need to give them a file that they can use in Navis or Revit, or auto CAD. So they can draw in all the Piping, Ductwork, etc...
The best file type would be Ortho or Point Cloud for this need?
And since they never have worked with aerials, what can I do to help them?

Thanks again, your input is much appreciated

 

[jahalnon]

My guess is they will need the 3d capability of a point cloud. Surveyors use laser scanners to do same which gives really good point cloud to pull data from. The drone just does it from the air instead of a tripod. It they were strictly looking down on the roof top and just want to create 2d linework for lengths and dimensions, then the final orthomosaic image file would suffice. But it should be scaled accurately to get good dimensions.

Carlson Photo Capture like Pix4d will give you a good georeferenced final orthomosaic image as well as digital terrain models. Especially if you are using RTK drone with GCPs, the final ortho is pretty good and comes in directly in the proper x,y space in the cad file.

Here is a small screen shot of the ortho image under the cad line work from survey points and some data from the point cloud.

 

[yarrr]

For example, I'm flying a huge rooftop of a building, where many pipes and duct work, and AHUs will be installed. I want to, need to give them a file that they can use in Navis or Revit, or auto CAD. So they can draw in all the Piping, Ductwork, etc...
The best file type would be Ortho or Point Cloud for this need?
And since they never have worked with aerials, what can I do to help them?

Thanks again, your input is much appreciated

Agree with @jahalnon , but wanted to add that there may be some confusion caused by the orthophoto format exported by Pix4d. For Autodesk products to read it, sometimes it needs to be resaved without the 'bigtiff' format. QGIS can take care of this (using LZW compression is a good balance of quality and size).

Long story short on your original question, there is no program available right now that will automatically take raster (or point cloud) UAV data and extract usable vector data of objects. Whether it is you or the CAD department, someone will be "tracing". Hopefully they are paying you well.

 

[Dave Pitman]

this guy shows a speeded up workflow of pointcloud to cad using this open source sofftware.

That is a good example, thanks for the share. Do you have links for the other vids in the series?

He does not identify the software he uses initially before moving to to Civil 3D?