Issues combining surfaces

[crewsmolly45]

Hello, I am super new to Civ3D. I am having issues with the way autocad combines two surfaces. I have tried slicing instead of using paste surface, but it seems you cannot slice a surface with a surface?

If I select the two surfaces and view them in object viewer, I can see exactly where I need it to "trim" the surface. If it would let me ID an point of intersection of the two surfaces, I could just build a new one myself, but it will not. Using paste surface (I have tried reversing the order of selection as well) does not give me the surface I am looking for. I need it to combine where they both intersect and trim the rest. 

Any advice on how to get this to work? I attached the DWG and a word file with pic for reference

[ChicagoLooper]

Hi @crewsmolly45 

Thanks for uploading your file.

Try this:

Adjust viewcube.....

[crewsmolly45]

Hi, thanks, yes I did try the paste surface. It is not giving me the correct end result.

[ChicagoLooper]

Can you upload a screenshot of the whacky result?

[crewsmolly45]

Two snips in this word doc, looking at it from the bottom. The top one is just viewing the two surfaces, uncombined, in the object viewer. But the view snip is taken from is what I need it to look like. Second snip is what using paste surface is giving me

[MichaelH13]

You can just post the images directly here in the forum 😀

When you paste surfaces together, you paste your ""top" surface into the "bottom" surface. The surface that is being pasted will overwrite the data where is it being pasted.

Depending on the order in which you paste surfaces, you will get different results. As you only have 2 surfaces, you can only have 2 different results.

 I got that result, same as ChicagoLooper.

Perhaps it would be helpful if you can describe what it is we are looking at and what result you are trying to achieve.

I can only guess that it looks like a waterfront with a berth area removed?

Why are you looking at it from underneath??

[ChicagoLooper]

@crewsmolly45 

The surface named SD 1 to 1 has two flaps that stick up in the air, above and beyond the surface named Berth 7. 

When two surfaces are being pasted C3D is looking at Points in Common, areas where the surfaces overlap. C3D then analyzes the z-values in the common areas and pastes the 2nd onto the 1st. You could say it’s a battle of Z’s, where one elevated surface wins by overriding the other and ending with a final surface that’s a nice and tight combination of the two. 

Due to those two ‘flaps’ in SD 1 to 1 sticking up above Berth 7, additional and unnecessary Z-values from the flaps are factored in causing the new surface to freak out and give unwanted results. 

Redesign (recreate) SD 1 to 1 without those two flaps (terminate flaps at the big ol’ flat area) and the new surface will be fine. A redesign is probably a lot easier compared to fixing that offending surface. 

Or……take SD 1 out of the equation (don’t use SD 1 at all) and just add feature lines to Berth which can be used to create that spillway (or whatever that cutout is).

[MichaelH13]

Eh, I'm an idiot. In fairness, I was thinking more about lunch than what I was looking at!

Is this more what you wanted??

 

All I did was edit the lines on the SD surface, I deleted the ones that protruded out above the berth. There is a slight tessellation on the front face, but I dont think that matters?

Using the isometeric view in model space helped identify exactly what lines to delete. Then simply up to Edit Surface - Delete Line on the menu. '

Hope this is more helpful!

[crewsmolly45]

Yes those are what I need removed. I am having trouble figuring out exactly where the surfaces intersect though, as both sides of intersection are on a slope.

[crewsmolly45]

Well, underneath since I exported a template from another program with Z values being positive below zero. I didn't feel like redoing it, so just looking at it from underneath. Also, I couldn't figure out how to paste a snip in the chat 😄.
Your snip at the bottom is very close, but it is skewing grade at the bottom. It should be a straight line across from the outer two points to where it meets the avoidance area in the middle.

Vs. viewing them at the same time just not combined:

I may be going about this the wrong way and need to try a different command?

[MichaelH13]

This is a look at the two surfaces in ISO view in model space. The problem you have is highlighted in yellow.

I removed the 2 lines in red (easy enough to do) to get my result, but it leaves a high point. You would need to edit the surface data back down to the same height as the face.

So I decided to play around a little. I have never worked with 3D faces before so it was fun working it out, but after doing what I described above, I get this result.

 

And seeing as you like the view from below.....

Any good?

[crewsmolly45]

Same! I have mostly just been watching amateur vids and playing around. You've got it nearly there, the only thing is that the slope of the avoidance area slopes down into the slope of the Berth. That's the trouble I am having with just building one surface, I have no idea where the two intersect in the slopes.

[MichaelH13]

Can you not just change the 3D face and set it at whatever point you need along the face of the berth? That's all I did.

[MichaelH13]

Have the two surfaces open in Civil3D, explode the surface so that you can manually edit the 3D faces and just set them where you want them to be. Then make a new surface from the faces and combine the 2. 

I don't know what design parameters are important for you. I can't see why what I have done would be any different from what you need, but I'm only learning and far from a pro. 

[crewsmolly45]

Thanks for your help!

[MichaelH13 · Accepted solution]

Because I have the time to play.....

 

Ignore the other side, I havent finished. Is that detail what you were wanting??

Working in 3D lines ain't easy, but I think I got there. I extruded a line across the berth grading side to make essentially a "cutting face" so I could see where the avoidance area intersected. After a bit of playing around I managed to align the faces up nicely and join the surfaces.

Any good?

[andrewpuller3811 · Accepted solution]

The easiest way to identify the location where the two surface intersect is to create a volume surface using the two surfaces.

The zero contour line will be the intersection line which you can extract from the surface as a polyline.

Then you use that polyline to create a border for each surface.

Then you can apply the borders to the corresponding surfaces.

Once the borders have been applied you can then paste the surfaces into a new combined surface.

If you need detailed steps, I can provide them.

[crewsmolly45]

Ah ha! Yes!!!

[crewsmolly45]

Thank you I will try this as well

[tcorey]

An easy way to find where two surfaces intersect, make a TIN Volume Surface. The 0 elevation contour from the volumes surface is the intersection of your two surfaces.