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Author Topic: Distortion UVW unwrapping a cylinder (Blender 2.49b)  (Read 10081 times)

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Offline ACDmvmkr

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Distortion UVW unwrapping a cylinder (Blender 2.49b)
« on: April 25, 2011, 04:53:38 AM »
I'm attempting to apply a texture image to a cylinder. After selecting all the faces in edit mode, the resulting unwrap always seems to meander all over the place, resulting in a distorted image applied.

Either the unwrap meanders like a snake, or if it comes out straight, the panes of the faces are all leaning over, like they've been sheared into trapezoids instead of symmetrical rectangles.

This makes it hard to apply a created image to the cylinder because it leans or twists about it. Tilting the image in the UV window does nothing for the problem as only the lines in the one direction can be aligned, the other ones perpendicular to them twist and wrap around the cylinder.





I've tried playing around with all the settings, but I can't see any changes take effect.

If I go thru and manually tweak each pane of the unwrap by selecting vertices, I can sometimes get a satisfactorily symmetrical image applied to the object (like a cylinder or a dish), but that is a horribly tedious operation, and then every time I resize the "map" on the image in the UV window for a better fit, it destroys the symmetry I'd just achieved and the panes are all uneven again. I figure there's got to be a better way to get a cylinder unwrap or a spherical unwrap????

BTW, playing with UV & orco, etc, made no difference either....

I've tried using the "UNWRAP" setting, the "CYLINDER FROM VIEW" setting, and the "SPHERE FROM VIEW" setting, but many times, no matter which plan view I select before unwrapping, the unwrap gives me this really stupid meandering result, sometimes even splitting the object up into two mirrored sides upon unwrapping, or scattering the individual face panes all over the place.

here are two cylinder unwraps from side and top plan views....

-side-


-top-


How do I stop this?
thx, Dave

Offline kat

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UVW Unwrapping a cylinder in Blender
« Reply #1 on: April 25, 2011, 05:01:33 PM »
Make sure your cylinder is seam marked similar to the following;

This usually happens for a couple of reasons (that are easy to fix).

  • 1) resizing or manipulating the object - in this instance Blender is basically still referencing the original shape/size of the object when the unwrap is performed, so naturally it deforms because it no longer represents the actual shape/size of the object.

This is fixed by using "Apply Object" on the object before unwrapping - select object (you need to be in "Object Mode" for this (toggle edit) and press "Ctrl+A" to open the pop-up menu, select "Scale and Rotation to ObData"

  • 2) using the wrong "Unwrap Method" - Blender can basically unwrap objects in two ways, 'relative' and 'absolute'. Relative uses "Angle Based" calculations, absolute forces Blender to use a "Conformal" calculation that 'conforms' to the objects shape.

This is fixed in Edit Mode by setting "UV Calculation" to "Conformal" instead of "Angle Based" (you may still need to use "Apply Object" to get this to work correctly). See below.

Using "Angle Based" tends to distort certain shapes

"Conformal" is much better for 'man-made' shapes that have hard contours and silhouettes

Additionally, if you find that you do need to manipulate the UVW map in the UV/Image Editor, turn on "Snap to Pixels" (this wasn't mentioned in the UVW tutorial on purpose by the way).

(you should be able to see an example file attached below)

Offline ACDmvmkr

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  • Posts: 45
Re: Distortion UVW unwrapping a cylinder (Blender 2.49b)
« Reply #2 on: April 26, 2011, 07:02:04 AM »
Thank You! Very informative!
Will play with these for awhile.

BTW - How long are these posts left available here on this board,
it would be nice to be able to refer back to them over time....

Offline kat

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Re: Distortion UVW unwrapping a cylinder (Blender 2.49b)
« Reply #3 on: April 26, 2011, 06:14:19 PM »
Everything is pretty much perminant so you should be able to view it whenever you need  ;)

 

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