Tracing topos - how best to do it?

I need to enter some PDF topos into sketchup, and my attempts at doing it with a mouse and the freehand line tool are horrible. I was thinking of using a digital tablet - will that work? I was thinking of getting a cheap one for $40 something.

What advice do you have for me? SU 2018 pro


In SketchUp 2018: use the ‘Freehand’ tool while holding down [Shift] to create a 3D-Polyline ontop of the topo line shown in the PDF. Now explode the 3D-Polyline into segments that you then weld into a better manageable curve.
3D-Polylines are easy to create without the interference of existing geometry. But they are very hard to controle, hence exploding followed by welding.

Unlike what is mentioned above for the ‘Freehand’ tool, I see no 3D-Polyline created in the latest web version. No matter of whether holding or not holding down [Shift], the tool ‘just’ creates manageable curves!

added: Is SketchUp 2022 (web and pro) the end of 3D-Polylines?

Are the contours in the PDF vector linework? Can you share the PDF so we can see what you’re working with?

Fredospline (trial) may be worth looking at if you’re tracing a lot of curves

This is one of two that I have to do. I have to draw a 2 car garage at the toe of the slope with an apartment above it, and allow for set back. I have to get the other scanned, but it’s dark grey for a retaining wall.

Can you share the actual PDF?

21.17926_TOPO (1).pdf (1.0 MB)

This is the other one that I need to get scanned

It is a recent survey. Why hasn’t it been supplied in a CAD format? I am 99.8% certain that those are printouts from CAD.

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Good idea - I will see if they can send me a auto cad file. The other, I have to take it to get scanned. I wonder if there’s a way to improve the contrast, like in photoshop?

If you trace it you don’t have to use the freehand tool. just pick a level of detail and draw edges over the contours. The level of detail is the approx. length of edges you use. When done with a contour. Triple click and use 'weld" to make into a curve. If you need to, at that point, you can use a tool such as “Curvizard / Smooth Contours”

You don’t need every detail. People put too much emphasis on adhering to the drawn contour. It’s only a rough approximation depending on the amount of data gathered in the field.

I agree with @Anssi, that looks like a CAD drawing. I’d contact the surveyor and see if he can provide a DWG file. That’s preferable to a vectored PDF, which in turn is preferable to a scan of a paper drawing. The most recent DWG’s I’ve gotten from surveyors had the contours already lofted to the correct height in 3D so all I had to do was select them and skin them with Sandbox Tools.