Remove extrusion of an object and return to original 2D object (green and red axis)


#1

Hello, I am sure this is a basic question, but I am starting on Sketchup and missing something (and stuck on my drawing).

I have modelled a large map drawing the terrain, and on a new layer lots of buildings on top. I need to remove the extrusion (gave it a 10 mm height) and somehow “intrude” and revert that terrain to the original state of drawing (in 2D when it was flat) but when i do use the extrude tool and try to “intrude” /“de-extrude” the object disappears, although I need to retain the original perimeter.

In order to simplify, and for test purpose, back to the basics I did open a new document, drew a rectangle, then extruded it updward. Then I tried to extrude the other way down to revert back to the original rectangle perimeter - the intrude does make the rectangle disappears, and the complete object vanish. (in my original drawing my terrain is huge and has many vertical points/lines, but I need to edit it, so I need to revert it back to flat).

Does one can flatten an object / intrude back to it original 2D drawing ? If so what tool can be used ? Many thanks for pointing me in the right direction.


#2

If you have access to SketchUp Pro, you could export a 2D DWG of your top view to full scale (using parallel projection) and import that back into SketchUp. There is also a flatten plugin, if I remember right it is from Smustard.

Anssi


#3

It’s not clear whether you just want (1*) the perimeters of the buildings “flat” on the created terrain or (one step further back), (2*) also the terrain flat including the perimeters.

You could apply the ‘Drape’ tool in the ‘Sandbox’ toolset.

1*) The terrain should be grouped.
Select the buildings, then ‘Drape’, then drape them onto the terrain.

2*) Draw a huge rectangular face underneath the model.
Select all, then ‘Drape’, then drape them onto the face beneath.

3*) Annsi’s method by exporting to 2D dwg, then import again that dwg.

4*) search for a plugin that has ‘projection’ capabilities. See the ‘Extention Warehouse’ from within SketchUp. (last icon in the ‘Warehose’ toolset).

Otherwise TIG or others might also have a suitable plugin for projecting geometry. See the Sketchucation forum: http://sketchucation.com/forums/viewforum.php?f=262


#4

The original flat face is still there on the bottom of the extrusion. You could just slide out a copy of it using Alt-Move–like dealing a card from the bottom of the deck. Then just delete the extrusion.

-Gully


#5

Portus v10.skp (2.4 MB)

Hi and thank you to Anssi, Wo3Dan and Gully_Foyle for taking the time to reply. What worked for me is the reply from Gully, worked great, very efficient. Thank you, thank you, thank you guys.

(In the attached document it is the purple section (the terain), that was creating problem, I needed to retrace its contours, but first had to remove the extrusion - Using the method : “slide out a copy of it using Alt-Move” - worked great).


#6

Great, except I slightly misspoke. We want to use Move-Copy, which is actually Ctrl-Move. Alt-Move is Autofold. Glad you got it to work; you must have done what I meant to say, not what I said.

-Gully


#7

Hi Gully. Confirming that what worked for me was the Autofold : Alt-Move. The other : Ctrl-Move move copy method, does part of the job as well, but after doing it and then deleting the extrusion, this method leaves all the edges.

So no I have done what you said, and not what you meant to say, and this works beautifully as per your first original quote : « The original flat face is still there on the bottom of the extrusion. You could just slide out a copy of it using Alt-Move–like dealing a card from the bottom of the deck. Then just delete the extrusion. »

So, as a summary [Alt-Move - Autofold], removes the extrusion + snaps beautifully back to the « bottom of the deck » , and reverts that terrain to the original state of drawing (in 2D when it was flat), allowing further editing of the 2D shape (indispensable for large and complicated terrains like in this example : Portus v10.skp file).

Thank you again.

Portus v10.skp (2.3 MB)

On a simple exemple file this is what the method you described, helped me acheive which is perfect (second rectangle in the middle) :

<a class=“attachment”


#8

You must have selected the verticals. There’s no other reason they would have gotten grabbed. I’ve done this card off the bottom thing a hundred times.

-Gully


#9

Look, @Luds, I’m terribly sorry that my error (saying “Alt” instead of “Ctrl”) has created more misunderstanding than it has resolved. Please let me clarify by showing you what happens on my screen. First, here is the effect of “Alt-Move”:

Now, here is the effect of “Ctrl-Move”:

Please give it another try. Don’t pre-select. Pick the Move tool. Then tap the Ctrl key, putting the tool in Copy mode. Then click the face, slide along the axis, then click again to place the copy.

-Gully