Using Sharp Edges in blender

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A quick tip by Alex Telford.

Alex writes:

I’ve found a lot of people add in their subdivision surface and use extra edge loops to sharpen the edges.
This creates an unnecessary amount of polygons.

The correct technique is actually to use sharp edges in combination with the edge split modifier, as discussed in the short video below


  • http://bensimonds.com/ Ben Simonds

    I wouldn’t say it was incorrect to use extra edge loops. It’s more controllable, and allows you to create more complex forms. Creasing is definitely a good option too, particularly for very sharp edges.

  • http://www.facebook.com/people/Justin-Barrett/100002826740190 Justin Barrett

    it definitely is required for some geometry(additional loops) and gives more control.

  • http://profiles.google.com/selecta.print selecta trafaret

    additional loops are cool for adding details, but creases can save some polygons.
    I hope in time we will see normal edge beveling in Blender like in Maya (I need it)

  • Gertjan Van Den Broek

    It looks like a good way to reduce the polycount of very complex scenes. But you do not get that *sheen* effect on objects when you use the edge split modifier.
    I prefer additional loops and sometimes edge creasing.

  • Jadmin

    You mean “unnecessary NUMBER of polygons”. So sick of people using “amount”.

  • Anonymous

    Thanks for the comments guys :D
    Thought I’d mention: extra loops with subsurf is great for getting a clean, beveled look. Edge creases are cool to use for sharpening up corners, and edge split is fantastic for getting a sharp edge without smooth shading over everything.
    I use it more for the shading than polycount, but it definitely helps keep the polycount down too :)

    In short I’m not saying “You have to use this rather than extra loops”, but “It’s a cool technique to add to your skill set” :D
    So your all quite right :D

  • Anonymous

    Darn, got caught by the blendernation language police :O

  • randomblenderdude

    I’m checking blender every now and then and I have always wondered what edge split does, especially that Andrew Price have always demonstrated that it [edge split] is very useful in eliminating render artifacts/weird-shadings.  
    Thanks very much Mr Telford for the tip and for explaining the basics.

  • http://MacroManJr.blogspot.com/ MacroManJr

    While we’re being all needlessly pedantic here…

    Here’s the grammatically-correct way to write what you wrote, Jadmin:

    >> You mean “unnecessary NUMBER of polygons.”  I’m so sick of people using “amount.” <<

    Notice where the periods are located–within the quotation marks.  And an English teacher might get on your case about starting your second sentence off so informally.  But it doesn’t really matter much, doesn’t it?  We all understood what you meant.

    When it comes to effective communication, that’s all that really matters at the end–did we clearly understand what was meant?  It makes you look quite supercilious to be making such a big fuss over such a small issue in such an unfriendly way, and to boast about your being “so sick” of people making such a common and trivial mistake.

    If you can offer correction (and if the problem’s really that big a deal to begin with), try making a suggestion in a friendly manner with an air of humility next time.  That way, you won’t have to suffer such a well-deserved reproof as this.

  • http://MacroManJr.blogspot.com/ MacroManJr

    What randomblenderdude said.  Plus my thanks, too.

  • Michael Dawkins

    Well, this is a particular way to say thank you.

  • Endre Barath

    Edge split/sharp edge is an important thing. But you must know, a modern videocard can render many polys very fast. So on a hipoly model the edge split may slow but many polys can fast.

  • http://www.facebook.com/profile.php?id=647665547 Jeff Shepardson

    Awesome, thanks for this Alex. That was one of the modifiers I’ve never used before, now I can indeed add it to my toolbox.

  • Anonymous

    Modifiers can be applied after you see the results are what you want. In some circumstances you’re even forced to apply them.

  • Metpinarci

    Very good tip . I must say I havent use that button, ever  .  

  • HiRes

    additional loops and sharp edges are differents ways to obtain differents results.

  • http://www.raymairlot.weebly.com Ray Mairlot

    The downside of this is that if you ever have to consider using a different 3D package the sharp edges ‘probably’ wont be compatible.

  • Pyroevil

    Use sharp edge is not good for all cases. For realisic scene , sharp edge always give a 3D feel. I don’t know how good is the crease option but the other way is to create bevel (not available for now in blender). You get a more realistic look like this because nothing is infinitly sharp in the reality (probably exeption for something sharp like a good knife). Strategically added more polygon is the price to pay for beautiful 3D.

  • Jumbo Rich

    Alex, you provided a very useful tip. I had tested the “mark sharp” before but it never worked as I expected it too, so it got forgotten. This is going to be tried again tonight on a project I’m working on right now. So thank you. Do you know if a multi-res modifier behaves itself when you mark sharp?

    Why somebody’s only comment on your help is “NUMBER NOT AMOUNT” is beyond me. In “some” respects I actually think “amount” might be considered correct, as you probably don’t know at the time how many polys you’re going to be creating when adding an edge loop. Semantics IMO.

    More of the same please :-)

  • http://twitter.com/DukeOfTime Drunk Oikopleura

    I didn’t know this technique and might help a lot for some of my particular stylized models. Thanks for sharing sir *tips hat*

  • Jumbo Rich

    Just had a quick lunchtime try at work (my job has nothing to do with CG!) and it looks like you can’t use edge crease with a multi-res modifier :-( It complains about the ordering of the modifiers for some reason.

    Now that is a real shame. The more I think about it, the more I remember that this is where I got stuck before. Advice welcome!

  • Asa Taylor

    So it doesn’t create extra faces, just edges and verts?

  • Giancarlo Mora

    yeah yeah, no the best way to say it… anyway now I know whats “mark sharp” for ! Thats why I like see tutorials ;D Thx Alex I enjoy it…

  • Anonymous

    Nice tutorial  :)

    This technique is great for game artists and is the same as adding smoothing groups in other packages. Most packages support smoothing groups/hard edges, but if you are exporting and then subdividing again, you might run into a few issues where the polygroups reduce in size.
    If you are working entirely in Blender, then a better technique might be Edge Creasing (Shift+E in Edit mode) as it doesnt split the faces and just defines the hardness of the edge.

    Good job :)

    @b7a9c0585e8ba5f5ad10797a1263a0d5:disqus
    EdgeSplit and Edge crease are different things.
    But you are correct, EdgeSplit doesnt seem to want to work with Multires, but edge creasing works well :)

    @google-20c8003584d6a9ff646800916343e5a6:disqus
    Yes, that is correct. This technique doesn’t adds faces, just verts. and edges :)

  • Jumbo Rich

    Glorious! I’m back in the game ;-)

  • Andreu

    Sharp edge vs. geometry… interesting topic. I’d say that it is important to understand both. IMO, the basic way is by adding geometry. Control loops are essential to modeling. Sharp edges can save polygons, but sometimes I’ve found them unreliable.

  • James Cowgill

    Periods are valid in and out of quotation marks.  From what I’ve read, outside is the traditional “correct” way of using them in the UK, while the U.S. has largely moved to being inside the quotation as being correct (probably for aesthetic reasons).  But, when it comes down to it and as much as English teachers believe otherwise, grammar rules are much only a suggest and it’s really a waste of time to get hung up on them.    

  • nxain

    Adding extra loops generally works better for game geometry.  If you edge split, then you’ll may need to wield the meshes back together, depending on how you’re going to use the geometry in game (in which case, you probably shouldn’t have bothered to edge split as you end up with the same problem after wielding).  The big question is the game engine and how smoothing is applied (importing smooth groups, auto-smoothing normals based on angles and etc.)  

  • Drxms

    Good tip i learned something new. 

  • Casper Smits

    The know-how is more important than the number of polygons. Edgesplit is useful for unreal objects and nice design stuff etc, as for 3D printing or creating photorealistic effects the extra edge loop is more used.

  • Benjamin Lindquist

    Indeed, that’s why edge creasing is risky. Edge split on the other hand is very unrealistic on subsurfed meshes in my opinion since it gets too sharp. If seen from a distance it might be good though. That’s why adding more loops is safest if you intend to go highpoly. I don’t see the point in avoiding a few more faces if you’re already using subsurf.

  • Anonymous

    Hi Jumbo, Thanks for the comments :D
    Regarding using edge split with multi-res, as you are not editing the base afterwards you can apply the edge split and then use a multi-res.

    Just remember as you are editing all the individual verts with a multi-res, you could wind up with some holes in your esh where the edge split was

  • Anonymous

    Correct :)

  • Haha

    You can slide the additional loops to control the shape of the corners as well.

  • Nick Rishel

    Actually, I believe this would double the polycount of any marked edge with respect to the renderer. Still better than the presumed tripling you get from loop edges and more than the edge crease. ;)

    Since you can apply shading differently across difference faces, I wonder where other uses for this might be.

    Regardless of the semantics, thanks for improving my understanding of another component of Blender. :)

  • Anonymous

    Thanks :D
    though this technique does not effect the poly-count at all, as poly, refers too the number of faces. it does however increase the number of vertices, but not a substantial amount as to greatly effect render-times.
    Using it to control shading is the primary use :)
    There are a lot of uses, I recently used this technique in the creation of a 5 point safety harness :D
    And your very welcome :)

  • Philip Witte

    Awesome, thanks for this information! I’ve been using Blender for a could of years now and have been manually splitting geometry up to get this same effect.

  • Harbler

    While we’re all being needlessly pedantic here, it’s worth pointing out that the punctuation style detailed in your post is peculiar to American English, and is by no means regarded as universally correct. Punctuation in the UK adheres to a rubric that is at once more flexible and more semantically robust than what we’re used to in the US.

  • Harbler

    Please also make note of the fact that “grammatically correct” does not require a hyphen, and that a double-hyphen is a poor substitute for an em- or en-dash (and that which dash you use will, as usual, vary based on where you are and whose rules you’re following).

    Finally, please refrain from conflating proper punctuation with grammatical correctness. They’re different things.

  • Robynsveil

    Precisely. The suggested solution works fine for Blender, but I develop a lot of items in Blender for Poser, which has that auto-smoothing thing that you do want for most of the garment but, say, not for a seam. And auto-smoothing creates this absolutely horrible artifact (looks almost like wrong-way verts) that only an extra edge-loop solves.

  • Sleepwalker

    I’m all for cunning linguist, but this is ridiculous  ;P

  • Budianto Chen

    sharp edges in blender is just separating the edges and definitely will make open edges. This is not really works for game artist, since it will double the vertex and edges. IMHO Blender really should have real smooth group to attract more game artists.

  • Budianto Chen

    and for the high poly modeler, this is definitely not the technique you will use, it just way too sharp, unless the renderer have the smooth crease feature as in Mental Ray.

  • http://profiles.google.com/haraldthi Harald Thingelstad

    Simply, thank you!

  • Anonymous

    This is exactly what happens when you import a model with smoothing groups into an engine anyway :)
    It’s the same with UV islands too…it all creates new verts.

  • Anonymous

    Edge Creasing (Shift+E in Edit mode) :)

  • Yoraka

    Hi, i’m french and my english is not good.
    I can tell you that this modifier decreased a lot of faces of my models. Thx for this tip.

  • justb

    For baking normals it doesn’t work. You want the smooth edge meeting the sharp edge so that bakes out to the low poly to look smooth.

  • Fouldo

    Sorry guys but I’m finding it hard to concentrate on the video knowing that someone has started a sentence with the conjunction “And” as seen here:

    “Notice where the periods are located–within the quotation marks.  And an English teacher might get on your case about starting your second sentence off so informally.”

  • Budianto Chen

    Yes, I prefer Shift+E for High Poly Modeling :)

  • Budianto Chen

    Thanks, I don’t really know how engine works. Thanks again, so it should be ok to use it for game engine I believe. :)

  • Anonymous

    Yea, hard edges/smoothing groups are fine for any game engine. It should be noted however, that if you are baking normal maps in Blender,  then you cant use the edgesplit modifier or smoothing groups on the low poly mesh as you will always get a nasty seam. This is because Blender doesn’t have the ability to bake the maps correctly due to it not having a projection cage feature, so you are better using something like xNormal instead.

  • Thomas

    Been wondering how to do that. Thanks!

  • http://www.twitter.com/holyonfire bria

    Just needed to know how to do this. Thank you!

  • Andre

    I would not call this the “correct method”, rather just “a method”.  This often will create issues with your mesh and gives you very little control, although works in many situations.  

  • Jdogg661

    There are a lot of things in reality that are sharp. When I cut wood to make cabinets the wood is so sharp if you run your hand over it, it will paper cut you like a razor blade. The reason we smooth, bevel, route, or sand down the edges is so everything we pick up or use doesnt cut the user as they use it. Same with glass also. Now maybe in nature things might be smoother but there is still plenty of sharp objects in nature also. A lot of man made things are designed to avoid super sharp edges mainly for the protection of the users, but  the smoothing has to be applied by us also or designed to not be sharp. A blade of grass can also cut you like a razor blade so ya there is plenty of sharp things not that i know them all just a few examples.

  • Jdogg661

    I think this is a good tip thank you for the time to put into it.