Jump to content

Sign in to follow this  
ohtakooooo

How to make side UV when I make poly extrude already has UV object

Recommended Posts

Hi

I downloaded 3D modeling Asset and it's has UV texture but Asset has only one polygon so I can't get a SSS to looks like realistic petal like this

eb5a28d6ca017af6c52114051acd83b2.jpg.6f0c0f8031b886a1d39792ceabade705.jpg

this is my ref. I want to make kind this feeling

 

but mine is

424421032_1copy.png.c9c4294658eabfbfd15fe2c176006bb4.png

 

So I just extrude it but, there has a problem. the side of petal is empty.

2.png.1522a1af66ce595a041816d297af5036.png

375032453_2020-04-076_10_50.png.87a10301ca05cc99bb146137f81f6ffa.png

How to make side UV?

 

Petal.zip

Share this post


Link to post

As soon as you add points to an object that already has a UV, you will break that existing UV, so all of that stage has to be done again now. If that object used a bitmap texture, then you would also need to add graphics for the new polys you added to that existing texture, and then realign / re-organise the UV space to take your additions into account and make the new UVs line up with your newly edited bitmap texture. However, in the case of something as simple as a petal I would imagine that you don't need 3 separate UV islands (front / back / rim) within the main map - you still need 2 (front / back) but now one of those islands should also encompass the new side/rim polys as well. 

 

So if that is the case, we can redo those UVs very easily with just 1 UV seam,  and simple Frontal Projection to give you the lslands you need. If you get that right you probably won't even need to edit the original image - just slightly scale down either the front or back UVs so that the new rim polys also fit within the area previously describing only the front.  Here's an example (higher poly than yours) that shows how those polys should be seamed and laid out...

 

1. Define your UV seam / edge selection as follows...

 

image.thumb.png.42ebaade1ebd2365e7bd8eb14f7e0747.png

 

Then go into UV edit layout, select the front and rim polys only, and do a frontal projection from an orthographic viewport, followed by a relax so that the rim polys become an extension of the front ones. Then do the same for the remaining back polys, and arrange both the UV islands over the existing image you can load into the UV Edit's UV window, This should give you a result broadly like below...

 

image.thumb.png.c40344187038185468cdbe5fe7272204.png

 

So now you can see the rim polys are part of the front face UV island, and once that front face has been aligned and scaled down slightly to match your bitmap, should give you the result you need. 

 

CBR

Share this post


Link to post
  • Topic Author
  • 16 minutes ago, Cerbera said:

    As soon as you add points to an object that already has a UV, you will break that existing UV, so all of that stage has to be done again now. If that object used a bitmap texture, then you would also need to add graphics for the new polys you added to that existing texture, and then realign / re-organise the UV space to take your additions into account and make the new UVs line up with your newly edited bitmap texture. However, in the case of something as simple as a petal I would imagine that you don't need 3 separate UV islands (front / back / rim) within the main map - you still need 2 (front / back) but now one of those islands should also encompass the new side/rim polys as well. 

     

    So if that is the case, we can redo those UVs very easily with just 1 UV seam,  and simple Frontal Projection to give you the lslands you need. If you get that right you probably won't even need to edit the original image - just slightly scale down either the front or back UVs so that the new rim polys also fit within the area previously describing only the front.  Here's an example (higher poly than yours) that shows how those polys should be seamed and laid out...

     

    1. Define your UV seam / edge selection as follows...

     

    image.thumb.png.42ebaade1ebd2365e7bd8eb14f7e0747.png

     

    Then go into UV edit layout, select the front and rim polys only, and do a frontal projection from an orthographic viewport, followed by a relax so that the rim polys become an extension of the front ones. Then do the same for the remaining back polys, and arrange both the UV islands over the existing image you can load into the UV Edit's UV window, This should give you a result broadly like below...

     

    image.thumb.png.c40344187038185468cdbe5fe7272204.png

     

    So now you can see the rim polys are part of the front face UV island, and once that front face has been aligned and scaled down slightly to match your bitmap, should give you the result you need. 

     

    CBR

     

    Thank you for your reply!

     

    In this case , Asset is made with just one rectangle polygon so, I should re-modeling it. Is it right?

     

    Ahbin

    Share this post


    Link to post
    7 minutes ago, ohtakooooo said:

    In this case , Asset is made with just one rectangle polygon so, I should re-modeling it. Is it right?

     

    No. I only used more polys because I thought it made clearer what was a rim and what was a front or back face 🙂 If the scene has many petals in it, you want to keep polycount per petal as low as possible. Your model will only have 6 polys (1 each for front and back, and just 4 for the rim you added), and that should be fine in this case. In fact the ONLY reason you would consider making this out of more polys is if you wanted to bend or otherwise deform a petal.

     

    CBR

    Share this post


    Link to post
  • Topic Author
  • 40 minutes ago, Cerbera said:

     

    No. I only used more polys because I thought it made clearer what was a rim and what was a front or back face 🙂 If the scene has many petals in it, you want to keep polycount per petal as low as possible. Your model will only have 6 polys (1 each for front and back, and just 4 for the rim you added), and that should be fine in this case. In fact the ONLY reason you would consider making this out of more polys is if you wanted to bend or otherwise deform a petal.

     

    CBR

     

    Thank you! I solved it!

    but I can't understand define UV seem part. (I think my poor English level is problem to understand)

    because.. Asset has only 1 polygon so there have no out lines of petal..

    Anyway but you mentioned about Frontal projection mapping and it's very helpful!

    I re-modeling it, extrude it and Frontal mapping it. and it's works!

     

    Thank you again!

     

    Ahbin

    1.JPG

    2.JPG

    Share this post


    Link to post
    10 minutes ago, ohtakooooo said:

    but I can't understand define UV seem part. (I think my poor English level is problem to understand)

    because.. Asset has only 1 polygon so there have no out lines of petal..

     

    I can clarify that. First off, in English, the word 'Seam' (here meaning the area where 2 UV islands meet) is a different thing to the word 'Seem' (meaning 'which appears to be the case').  

     

    Secondly, you do in fact have 6 polys in your mesh, but you haven't UV'd them correctly yet, so they appear in the editor overlaid atop each other, so that it looks like just a single UV poly. You are getting away with that here in your result because the edge thickness on your leaf is so tiny, that the human eye doesn't notice that the material on them is technically wrongly mapped.

     

    CBR

    Share this post


    Link to post
  • Topic Author
  • 13 hours ago, Cerbera said:

     

    I can clarify that. First off, in English, the word 'Seam' (here meaning the area where 2 UV islands meet) is a different thing to the word 'Seem' (meaning 'which appears to be the case').  

     

    Secondly, you do in fact have 6 polys in your mesh, but you haven't UV'd them correctly yet, so they appear in the editor overlaid atop each other, so that it looks like just a single UV poly. You are getting away with that here in your result because the edge thickness on your leaf is so tiny, that the human eye doesn't notice that the material on them is technically wrongly mapped.

     

    CBR

     

    Oh... I spelled wrong seem *seam... haha...😂

     

    Ok I understand frontal mapping is wrong method because thickness is overlap a top each other. Ok I followed it. 👍

    You know the cherry blossom has no thickness. so I think using the SSS is kind not fit in my case. If I want to make my ref IMG feeling it should be stacking each other. am I right? But I need petals are scattered and floating on water surface so I change SSS to backlight shader.

    Is it getting right way to doing correctly?

    Share this post


    Link to post
    13 minutes ago, ohtakooooo said:

    You know the cherry blossom has no thickness.

    That is not strictly true, either in the real world or in 3D space. But your point remains 'Is SSS going to be the right way to go here ?', and like you, I speculate that 'No' is the answer, because in terms of meaningful thickness it can use I think you are correct.

     

    I also agree that the backlight shader is a good thing to try next, and course you must have no thickness in your model for that to work properly.

     

    However, implementing that might be awkward to an extent, and still might not give the effect you are looking for, because ultimately, that shader is designed for lamp shades and situations where there is light behind the surface in question, something that almost certainly wouldn't be the case if your petals are on the ground or floating on water. But the only way to know is to try it and see, and doing that might involve preventing your back light (the light itself) from being occluded by the ground / water surface, which you can do in the light properties / include tab.

     

    CBR

     

     

    Share this post


    Link to post
  • Topic Author
  • 2 hours ago, Cerbera said:

    That is not strictly true, either in the real world or in 3D space. But your point remains 'Is SSS going to be the right way to go here ?', and like you, I speculate that 'No' is the answer, because in terms of meaningful thickness it can use I think you are correct.

     

    I also agree that the backlight shader is a good thing to try next, and course you must have no thickness in your model for that to work properly.

     

    However, implementing that might be awkward to an extent, and still might not give the effect you are looking for, because ultimately, that shader is designed for lamp shades and situations where there is light behind the surface in question, something that almost certainly wouldn't be the case if your petals are on the ground or floating on water. But the only way to know is to try it and see, and doing that might involve preventing your back light (the light itself) from being occluded by the ground / water surface, which you can do in the light properties / include tab.

     

    CBR

     

     

     

    WOW! Thank you sir!

    It's glad to hear that I get in into right track

    I will gonna try! Super Thank you sir!

     

    Ahbin

    Share this post


    Link to post

    Join the conversation

    You can post now and register later. If you have an account, sign in now to post with your account.

    Guest
    Reply to this topic...

    ×   Pasted as rich text.   Paste as plain text instead

      Only 75 emoji are allowed.

    ×   Your link has been automatically embedded.   Display as a link instead

    ×   Your previous content has been restored.   Clear editor

    ×   You cannot paste images directly. Upload or insert images from URL.

    Sign in to follow this  

    • Recently Browsing   0 members

      No registered users viewing this page.

    ×
    ×
    • Create New...