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Eric Brown

Polygon Shader Problem

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Hopefully someone can help me out. I'm rather newish to modeling however Ive tried using both parametric modeling using Booles and polygon modeling using splines to recreate the image attached to this file. Its a Heart Camera surgeons use. Ive also attached my scene file with 3 different ways I tried creating the object however I keep running into a problem once I get to the same point. I believe its a shader or N-gon issue based on the topology I have created, It seems as though whenever I attach 2 sets of polygons that are on different planes the topology gets messed up beyond repair. Any help would be greatly appreciated. I tried to start fixing it however i believe in the end there will still be some shader issues and it will be unusable nonetheless on top if it taking to long to fix. I ran into a similar problem around a year back and pretty much quit c4d because I wasted so much time trying to fix something similar to this and couldn't come up with a solution.

 

Does anyone know of another way I can create this object that is fast and where I wont run into this issue?

3438456_rdax_80.jpg

Heart Camera.c4d

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Yep, this is the sort of surface where booles and splines can't really cope. It'll be proper SDS poly modelling that saves the day. This is not particularly fast unless you are very good at it, but it will produce a result that is professional and superior in every way to using splines or booles.

 

We do need rather specific topology to do this well. If you give me half an hour I'll show you what that is...

 

CBR

 

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OK, here's the first 8 stages of that...

 

1. Get a cylinder, 16 segments, no caps, on Z+, then make that editable and delete half the model along Z, then place under symmetry, but then turn it off.

Now, using the Line Cut tool (visible only off) and the right orthographic view, cut the curve you need into the cylinder something like this...

 

1349068261_HeartCam1.thumb.jpg.81890859e7e8a2a6b0414900a5e12554.jpg

 

Mine is only an approximation but you get the idea... the main thing is to add points wherever you need them to describe the curve, and irrespective of the topology flowing from left to right. But try to keep them evenly spaced.

 

2. Next step is to go to Poly Mode and delete all the polys above the line. Now, in the same view, ignoring the first 4 points from either end, Line Cut down from each point to the base of the cylinder.  If in doubt use the pic below as a guide as to which points should get those cuts. We need quads everywhere , so make sure you don't create any triangles while you do this.

 

At this point I used Edge mode and Ctrl+ Slide tool to duplicate the perimeter edge giving me this nice control loop.

Here it is, with Symmetry turned back on, and with the model placed under subdivision so we can check our curves...

 

 614604940_HeartCam3.thumb.jpg.e8a6d5f799c8816847cb0910f64a3b27.jpg

 

3. Next we need to bridge some edges to the centerline. Edge Mode, Path Select, and grab these edges.(left pic below)..

 

373489269_HeartCam4.thumb.jpg.c3e04fbcefcf747c26599b378bb253ae.jpg  1147189952_HeartCam5.thumb.jpg.5efc626429c96edc738475bedd704d17.jpg

 

... and ctrl-drag them with the move tool towards the centerline on X. Then, in the coordinates manager, zero out x scale, and set x position to 0, giving you the result on the right there...

 

4. Now we need the Loop Cut Tool to insert the following loop, which we will do in Edge Distance Mode so that stays straight. This will be the basis of our indent later.

 

1777619892_HeartCam6.thumb.jpg.a615e8c2df18459a11754d8ca851b9d4.jpg

 

5. Now we just need to close the holes with only quads, which I did using Bridge and Close Poly Hole, like so...

 

881231812_HeartCam7.thumb.jpg.45b93262c2ce399bc660afcaa34499d3.jpg

 

Note the extra edge I have cut in at the bottom to keep that section quads. Triangles on curves are a cardinal sin in SDS modelling, so we must avoid them at all costs, but here we need that extra line anyway, to better define the slightly rounded corner on the indent. 

 

6. Lastly we need to select all the polys on the curve and having made sure that we have Delete Polys on Centreline ticked in the Symmetry, inset (Extrude Inner) them to get this second control loop. Now, when we place this under an L3 Subdivision Surface object we get beautiful curves, and no surface artefacts.

 

Let me know when you've got this far, and if you need additional help cutting in the inset section in the center and the lights.

 

 

Heart Cam 8.jpg

 

CBR

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  • I just got back from a shoot, thank you so much! Ill do this tomorrow and get back to you, its 10pm where I am. From how you described things there is so much I need to learn about modeling. Wow I really should have asked for help on this site a lot sooner.

     

    Thanks again!

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    Oops - just seen you are on R17. Some of the above uses R18 knife tool commands.

     

    To translate:

     

    Where I refer to Line Cut, that is Knife Tool in Line Mode in R17.

    Loop Cut is the same Knife tool in Loop Mode.

     

    But there is a bigger issue in Step 1 - you can't do multi cuts within a single polygon with old knife tool.

    In that case, you're going to have to insert the vertical loops first, and then cut the curve from point to point.

    Rest of it should be OK.

     

    Good luck, let me know if you get stuck !

     

    CBR

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  • When you say insert the vertical loops first what are you referring to exactly? Sorry I dont see anything referring to "vertical Loops" in the step one. The only directions I see is to use the Line Cut or for me Knife Tool in line mode to cute the curve in the right orthographic view.

     

    For future reference would it be worth it for me to get r18 or r20 for that matter, is modeling that much more efficient with those versions of c4d?

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  • I'm doing it now, are you referring to step 2 when you say vertical loops?

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    2 minutes ago, Eric Brown said:

    I'm doing it now, are you referring to step 2 when you say vertical loops?

    Yes, those vertical cuts. If you are doing them first, do them as loop cuts that all go the way round the model, and you need 1 for each point on the curve initially. When you have the curve cut in, and the polys above that line deleted, you can then double click some of those loops to dissolve them, where they are not needed, and it's at this point you'd use my pic as reference to see which ones to dissolve, if that makes sense ?

     

    CBR

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  • Yea it does, thanks!

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  • Can I leave the loops? When i try to dissolve them I start to get weird n gons?

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    No, we can't just leave them. Easier to do it for you than explain every step because the solution you need is a bit different to my initial version...

     

    There you go - all sorted in the below... hopefully you can carry on from there...

     

    Heart Camera 2 Fix.c4d

     

    CBR

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