Author Topic: Decals on a sphere?  (Read 222 times)

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Offline nönöbär

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Decals on a sphere?
« on: November 30, 2019, 08:38:36 am »
Well, this is sometihng I am experimenting a bit, but without success so far.

I know how to make own decals, used this for several models now. But now I need to make a decals (a name) that should be located on a sphere.

If I just make a name decal and put it on the sphere, it does not look like good because it has not the right "curvature" (don't know if this word explains it - sorry no native english speaker).

So does anyone kow how to make such a decal that is bend the right way that it looks "good"?


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Online TheChronicOne

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Re: Decals on a sphere?
« Reply #1 on: November 30, 2019, 01:10:14 pm »
Oooh... I have some ideas...  If it's just text, grab a marker and write the text onto an orange....... then peel it and you'll be getting closer to having a template. You'll have to cut gaps in in at certain places to get it to work but after a bit of trial and error you could hone in on something that works then you can replicate the orange peel in your paint program. Think of map projections of the Earth.  Of course, things will depend on placement and orientation.



Worth a shot!



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Offline NARSES2

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Re: Decals on a sphere?
« Reply #2 on: December 01, 2019, 06:02:12 am »
There is geometric way of transferring the curvature (yes it is the correct word  :thumbsup:) onto a flat surface, but I really can't remember what it is. The Earth's globe to a flat surface uses the Mercator projection, but I'm not sure if that's the general one or specific to a the Globe ? Might be worth a search on-line though ?

Sorry I can't be  more helpful.
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Offline joncarrfarrelly

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Re: Decals on a sphere?
« Reply #3 on: December 01, 2019, 12:53:09 pm »
Mercator is one of many map projections, and is one of the most distorted, it does not
map back to a sphere.

The easiest way is to do it is simply one letter at a time.

Cutting darts (triangular cutouts) in the backing film between the letters may also work,
depending on size and length.
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Online TheChronicOne

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Re: Decals on a sphere?
« Reply #4 on: December 01, 2019, 01:44:05 pm »
Hence "projections" in my original post just as a starting point. The picture was reference only as one of many examples just to get the brainstorming going.

I tried to find a picture with text split by one of these but I couldn't (quickly) but I think that would help explain what I meant. I'll try again later.  ;D

EDIT:  Nevermind, mine isn't Mercator anyway!  :o  I read something wrong I think. Hell, just ignore me.  ;D   Splitting them up into individual letters like Jon says sounds like it would work pretty darn good with minimal fuss.
« Last Edit: December 01, 2019, 02:01:57 pm by TheChronicOne »
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Online rickshaw

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Re: Decals on a sphere?
« Reply #5 on: December 01, 2019, 08:00:55 pm »
Individual letters would work but you would need a line on which to place them, to make sure they are all aligned properly.   I would recommend working out the circumference of the object you want the decals to be attached to and drawing a single line on it.  Then attach the decals.  I am sure there is a mathematical way of drawing a set of curves on a flat surface to represent the circumference of a sphere but it is beyond me!   :banghead:
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Offline zenrat

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Re: Decals on a sphere?
« Reply #6 on: December 02, 2019, 12:27:50 am »
This is the sort of complicated projection they made us do in engineering drawing classes instead of interesting stuff like designing vehicles.
I can't for the life of me remember how to do it mathematically or on paper but if the name is aligned with what on a planet would be called a line of latitude then the letters would have to be in a curve of radius equal to the length of a tangent drawn between the centreline of the name on the surface of the sphere (the line of latitude) and the spheres vertical axis.
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Offline joncarrfarrelly

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Re: Decals on a sphere?
« Reply #7 on: December 02, 2019, 12:47:41 am »
Individual letters would work but you would need a line on which to place them, to make sure they are all aligned properly.   I would recommend working out the circumference of the object you want the decals to be attached to and drawing a single line on it.  Then attach the decals.  I am sure there is a mathematical way of drawing a set of curves on a flat surface to represent the circumference of a sphere but it is beyond me!   :banghead:

A line isn't that hard to make a line on a sphere, here's a quick and dirty way, the same basic method
is used to draw waterlines on boat models.
http://manningkrull.com/manningmakesstuff/drawing-latitude-and-longitude-lines-on-a-homemade-globe/

https://www.modelerscentral.com/tools-paints-glue/hand-tools/marking-measuring/waterline-marker/

A regular drafting circle template also works provided the sphere isn't too large, you just drop
the appropriate diameter opening down over the sphere to where you want the line.
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Offline NARSES2

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Re: Decals on a sphere?
« Reply #8 on: December 02, 2019, 05:54:01 am »
Mercator is one of many map projections, and is one of the most distorted, it does not
map back to a sphere.


I remembered that latter on Jon, but for the life of me can't remember what the others are. It's all a very long time ago  :-\
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Offline PR19_Kit

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Re: Decals on a sphere?
« Reply #9 on: December 02, 2019, 06:49:32 am »
There's BUCKETS of them, some very weird indeed!  :o

https://en.wikipedia.org/wiki/List_of_map_projections
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Offline zenrat

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Re: Decals on a sphere?
« Reply #10 on: December 03, 2019, 01:54:41 am »
Most commonly used projections distort the Southern Hemisphere (understandable given most land mass is North of the equator as were the mapmakers) which can be see by how far down the equator is.
However, I favour MacArthur's Universal Corrective Projection.

If anyone is interested in this subject and wants some reading I recommend A History of the World in Twelve Maps by Jerry Brotton.
Fred

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Offline NARSES2

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Re: Decals on a sphere?
« Reply #11 on: December 03, 2019, 05:41:49 am »

If anyone is interested in this subject and wants some reading I recommend A History of the World in Twelve Maps by Jerry Brotton.

I'll endorse that  :thumbsup:

For some reason I now can't get Pythagoras' Theorem out of mind ? Mind you I did once have to write it out 500 times (longhand) for talking during a maths lesson. Reckon I could sue the school for child cruelty if that happened now  ;D
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Offline Rheged

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Re: Decals on a sphere?
« Reply #12 on: December 03, 2019, 11:17:00 am »
I do like McArthur's map!!  As to Pythagoras,   one American first nation lady had two sons and sat on an exotic animal skin whereas the others didn't.  Thus, "the squaw on the hippopotamus  is equal to the sons of the squaws on the other two hides".........or something like that.


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Offline NARSES2

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Re: Decals on a sphere?
« Reply #13 on: Yesterday at 01:29:36 am »

Sorry, I'll go and hide elsewhere..........

After that nowhere you can go will save you from the searching masses  ;D ;D ;D
Decals my @r$e!