About size of flattened sticker and formed sticker


About size of flattened sticker and formed sticker
#1
Hello,
do the dimensions of the flattendd stickers and formed stickers have to be the same?

Until a few weeks ago this seemed like a useless question especially for cylindrical stickers, but lately this is no longer the case!

in the regulation to create the stickers there is talk of measuring them in LDU, but it is not required that they are exactly the dimensions indicated in the description.
And this has been interpreted as such by me, by the auditors and by the administrators until recently.

For a few weeks I have seen that they are trying to make the stickers the exact size shown in the description.
They say: the difference is minimal, a few hundredths of a millimeter, you can't see it.
Agreed, perhaps, but the opposite is also true.
It depends on how you deal with the problem of creating a new set of stickers and how you want to act on the ones already made.

When I have to create a new set of stickers I do this: I check which pieces should be attached, I check if there are already any stickers with the same shape (the stickers help in this), I make the flat version in various subparts and then the formed one is born accordingly. This means that reviewers have until 6 or12 subparts to check for a single sticker, but once the subparts are OK you know that the two mainparts are perfect and you don't have to check that they match. The explanation that has been given, however, is not to reduce the number of subparts.

With what is being done now, however, it becomes practically mandatory to look for a flattened stickerback that is compatible and the formed one. Then you have to create the flattened and formed version which are not exactly the same, so the game of subparts cannot be done. Drawing the sticker formed in this way will cause a lot of imperfections due to rounding that will require additional condlines. Or do you decide not to consider them a priori?

The way you are trying to edit the official stickers is somewhat questionable. Add slices of a few tenths of LDU to the ends of the flattened version, leaving the formed sticker unchanged, when it would be enough to change once and for all the stickerback formed and the two subparts at the ends to have everything consistent as it has been done so far.
It's a lot of work that we didn't feel the need for until a couple of weeks ago, but if you really want to do it, do it well.
Also because otherwise a new sticker how should I do it? If I do it as I have done so far, you will surely tell me that those slices are too thin and do not fit.

So I repeat the questions.
Do flattened and formed stickers have to be the same length?
For me: Yes
Do you need to round the stickerbacks to the nominal size of the description?
For me: No

Rather, if you think that the flattened version can have reusable dimensions from a flat only sticker with nominal size, then let's create a second version (a, b, c...) in which in the description we say what to use that stickerback for stickerback020x038a.

Massimo
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RE: About size of flattened sticker and formed sticker
#2
(2025-12-16, 0:23)Massimo Maso Wrote: Do flattened and formed stickers have to be the same length?

Yes but exceptions can be made

(2025-12-16, 0:23)Massimo Maso Wrote: Do you need to round the stickerbacks to the nominal size of the description?

As an author, I would expect the actual sticker back dimensions to be exactly same as in the description. For normal parts, 3 digit precision is plenty with very few exceptions. So, to answer your question: yes, without exception.

I think the spec is clear on both these points but I'm willing to clarify if needed.
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RE: About size of flattened sticker and formed sticker
#3
Question is "exactly"... imho, should simply be "the same" within (to be defined) a few %
- should sticker size be defined as the sum of chords of facetized surface, or the sized of the smooth arc?
- because of sticher thickness, length of top is different from length of bottom
...and human eye is unable to see a length difference of a few %!
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RE: About size of flattened sticker and formed sticker
#4
I have another question about this:
Quote:Then you have to create the flattened and formed version which are not exactly the same,

What aren't they the same? If the curved top face is just the flat top face broken into parts for the curve they should match.
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RE: About size of flattened sticker and formed sticker
#5
Maybe the question is: Is the method used by Philo allowed? 
As I understand it, the stretching (adding surface) and shrinking is an atempt to avoid another complete rework of the subfiles.

On the other hand, it must be possible to adapt the length of the end-sections, with the rounded corners, and then adjust the stickerback-file, and reuse the all the middle sections. If not, why isn't that possible?

As I've said before there is no rule stating that the formed sticker must match the 0.2 ldu from the edge-rule.
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RE: About size of flattened sticker and formed sticker
#6
(2025-12-16, 17:18)Magnus Forsberg Wrote: As I've said before there is no rule stating that the formed sticker must match the 0.2 ldu from the edge-rule.

Also, the edge rule isn't a rule, it's a strong recommendation with justified exceptions.
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RE: About size of flattened sticker and formed sticker
#7
The sticker back spec exists to standardized sticker creation to prevent near identical file proliferation and so that we're not arguing about tenths of an LDU. This thread shows that that mission has some distance to travel still.
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RE: About size of flattened sticker and formed sticker
#8
(2025-12-16, 15:03)Orion Pobursky Wrote: I have another question about this:

What aren't they the same? If the curved top face is just the flat top face broken into parts for the curve they should match.

Philippe Hurbain
Question is "exactly"... imho, should simply be "the same" within (to be defined) a few %
- should sticker size be defined as the sum of chords of facetized surface, or the sized of the smooth arc?
- because of sticher thickness, length of top is different from length of bottom
...and human eye is unable to see a length difference of a few %!



With the official stickers released so far, the accuracy is guaranteed at 1/10000 LDU, on the decorated upper face.
The lower one is obviously shorter for folding and we don't care. What comes comes.

Even after we have standardized the length of the flattened stickerback, we should aim for this precision in order to be able to use, as I wrote before, the mounting of the flattened sticker formed by the rotation of subparts.

The length I mean is the sum of the length of the chords of facetized faces that make up the sticker. It is useless to aim for the ideal arc of circumference since no sticker is made in this way, not even if made with Texmap because you do not have the real cylindrical surface on which to project it.

With the solution currently proposed by Philippe, equality is no longer guaranteed, in fact only the length of the flattened version has been changed. And this is wrong.
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RE: About size of flattened sticker and formed sticker
#9
(2025-12-16, 17:18)Magnus Forsberg Wrote: Maybe the question is: Is the method used by Philo allowed? 
As I understand it, the stretching (adding surface) and shrinking is an atempt to avoid another complete rework of the subfiles.

On the other hand, it must be possible to adapt the length of the end-sections, with the rounded corners, and then adjust the stickerback-file, and reuse the all the middle sections. If not, why isn't that possible?

As I've said before there is no rule stating that the formed sticker must match the 0.2 ldu from the edge-rule.

In my opinion, Philippe's solution is wrong, because it saves the work for the current official stickers, but complicates it for future ones and leaves the doubt about which size to take as a reference. It introduces useless thin faces and forces you to work with directly curved drawn stickers.

The work to be done is not a complete rework of the stickers.
This must be done:
1 - Draw the formed stickerback (e.g. 50950b01) so that the total length of the top face is identical to that of the stickerback to be used (difference less than 1/10000 LDU).
In my opinion, this must be done in any case to have consistency in the future. fair, you have to choose the flattened stickerback well so as not to have second thoughts in the future.

2a - For stickers made with subparts, modify the two extreme subparts to fit the new stickerback.
This gives once and for all the reference to be used in the future for those who want to use this way of creating stickers. In my opinion it is the right way to do it.

2b - For directly drawn curved formed stickers, you need to lengthen the ends as necessary to adapt them to the new stickerback.
This is the only part that Philippe's proposal could save, but at the cost of a questionable difference between flattened and formed stickers.

3 - Review and approval work on stickers.


Do you want to save yourself all this? Leave everything as it is, avoiding wanting to standardize to 0.2LDU the sizes of stickers that are not.
With stickerbacks you have already done a great job of standardization.
This part is an unnecessary burden of work.
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RE: About size of flattened sticker and formed sticker
#10
(2025-12-16, 17:34)Orion Pobursky Wrote: The sticker back spec exists to standardized sticker creation to prevent near identical file proliferation and so that we're not arguing about tenths of an LDU. This thread shows that that mission has some distance to travel still.

Can you give me an example of near identical proliferation, because I haven't seen any. At the moment it doesn't seem to me that there are any official stickerbacks with overlapping sizes.
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RE: About size of flattened sticker and formed sticker
#11
Welcome to the nitpickers department! Stickers do add a lot to a model, but they are just that - STICKERS -. Their exact geometry has no impact on the model... Imho formed stickers would be fine if they were a simple projection of the flat one, roughly in the direction of the average normal of the covered surface, top surface of the sticker translated by sticker thickness from bottom surface.
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RE: About size of flattened sticker and formed sticker
#12
Here's what I think is the right answer and we can discuss:

- Stickers shall be modeled flat and the dimensions in the sticker back file will accurately represent the dimensions in the file name. The 2-3 digit precision is perfectly adequate.
- For formed stickers, the top (i.e. patterned) face of flat stickers will be cut and folded such that if unfolded, they are the same size as the flat sticker. I acknowledge some there may be some slight imprecision in here for rounding an what not.

TLDR;
The flat sticker will be the size the file says it is.  The formed sticker should be derived from the flat sticker as best as possible.
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RE: About size of flattened sticker and formed sticker
#13
A few tests should be done taking into account that at this moment you have the "perfect" correspondence between the length of the flat and folded sticker.
With the new rules you could lose it, and in my opinion it is a missed opportunity to maintain or improve the quality standard.

Folded stickerbacks will always have 4 digits of precision in some points that correspond to the vertices of the face on which they are attached and in the terminal area. I believe that this is impossible to eliminate unless we accept interpenetrations of sitckerback and part.

For example, for stickerback 61678b02 (only two faces), the vertex circled in red will have 4 decimal places of precision.
   
On the other hand, the blue-circled vertex may have 2 or 3 decimal places, losing the parallelism between the top and bottom faces.
   
The vertex circled in yellow, I'm afraid they have to remain at 4 decimal places to avoid gaps.
   

So, do you want to reduce the number of decimal places to reduce file size?
Good, but let's do it wisely.
Also so as not to redo the work several times.

Be careful, however, because if the top of the stickerbacks are moved then we would have to redo all the stickers, official and not.
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RE: About size of flattened sticker and formed sticker
#14
Maybe I was unclear.  

What I meant was 2-3 digit precision is fine for flat stickers.  4-5 digit is perfectly acceptable for formed stickers to conform to primitive vertexes. 

My point was that an unfolded formed sticker should match (with consideration for rounding errors) the flat sticker.
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RE: About size of flattened sticker and formed sticker
#15
I return to the fact that there must be correspondence between the total length of the flat and folded sticker.
This is important in my opinion because it allows us to do the job only once and, if there is a programmer who assists us, even do it automatically.

I'll start with stickerback 61678b02 because it only has two sides and it's easier to describe the process.
Here the method is objectively excessive, but it is mechanically the same that you can also use for a sticker with a very high curvature and multiple faces such as 6143b01 and 93273b01.

To create the 6177969bc01 sticker you need to fold the flat sticker and fit it to 61678b02. You can do this by projecting the design onto the slanted faces or by splitting the design in two and rotating the resulting two subparts.

The first solution has the following disadvantages:
 you have to design a new sticker, without reusing the flat design already made;
 the resulting sticker is not perfectly flat, especially when you start rounding the vertices;
 you must arbitrarily choose the angle at which to project the initial design;
 if there is any detail on the margin you may lose it with the projection and you have to repeat the operation.

It has the advantage that all the folded sticker is in one file.

The second solution has the following disadvantages:
 it involves a number of subparts equal to the number of faces to be covered; 
 it takes a little foresight if you want to reduce the number of decimal places.

The second solution has the following advantages:
 it can be automated, there is nothing to decide;
 everything that is in the flat design is reported directly in the peigato sticker.
 it can be applied for any folded sticker, any curvature it has and any number of faces it has.

Basically, once you've decided on the flat design and know which piece it's to be applied to, you don't have to worry about how to bend it.

Ok, the procedure:
Step 1: Draw the flat sticker
   
Step 2: Cut the sticker along the fold lines
   
Step 3: Create the two subparts
   
Step 4: Move the origin where it is needed to make the bend. *
       
Step 5: Join and simplify the vertices due to the cut, round the inner points of the design as you like (to as many decimal places as you prefer), except those on the cut line and those on the final edge. (On red lines and inside the red circles).
   
Step 6: Arrange the names in the main parts referring to the two subparts now created and you have the two stickers ready (flat and folded).

Same thing for these two more complicated stickers in terms of number of faces. 6142271i and 6253811ab.
       
           

However, the whole thing works if you keep the total lengths

* This is because the center of rotation is on the bottom face of the stickerback and not on the vertex of the top face.
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RE: About size of flattened sticker and formed sticker
#16
(2026-01-22, 18:55)Orion Pobursky Wrote: Maybe I was unclear.  

What I meant was 2-3 digit precision is fine for flat stickers.  4-5 digit is perfectly acceptable for formed stickers to conform to primitive vertexes. 

My point was that an unfolded formed sticker should match (with consideration for rounding errors) the flat sticker.

For me the error must be as much as possible 0, otherwise you will have gaps.
It's something you have to check once now, or when you create a new sticker, and then it's up until the next revision of the rules (hopefully forever).
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RE: About size of flattened sticker and formed sticker
#17
(2026-01-22, 18:55)Orion Pobursky Wrote: Maybe I was unclear.  

What I meant was 2-3 digit precision is fine for flat stickers.  4-5 digit is perfectly acceptable for formed stickers to conform to primitive vertexes. 

My point was that an unfolded formed sticker should match (with consideration for rounding errors) the flat sticker.
I maintain that the dimension match between flat and formed stickers can be pretty loose, 1 or 2 Ldu over 40 ldu size is completely unnoticeable. Another consideration is that only the formed sticker size must be reasonnably precise to fit the part it's applied to. But flat version is essentially used for bill of materials so the needed dimension precision is pretty low.
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RE: About size of flattened sticker and formed sticker
#18
Have you tried Lasse Deleurans PatternFolder?
It produces a pretty good folded pattern. I used it making the stickers for the Dodge Challenger, set 75893.
When I used it, it only folded the pattern, and I had to tweak the surface to get a sticker, instead of a part, surface.

Today it folds the top surface, but projects the sticker backside on the y-axis. Not good.

But, I think it must be possible to tweak the shapes in Lasses tool, so that it will create a formed sticker top surface, to a defined stickerback subfile.
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RE: About size of flattened sticker and formed sticker
#19
(2026-01-23, 12:52)Magnus Forsberg Wrote: Have you tried Lasse Deleurans PatternFolder?
It produces a pretty good folded pattern. I used it making the stickers for the Dodge Challenger, set 75893.
When I used it, it only folded the pattern, and I had to tweak the surface to get a sticker, instead of a part, surface.

Today it folds the top surface, but projects the sticker backside on the y-axis. Not good.

But, I think it must be possible to tweak the shapes in Lasses tool, so that it will create a formed sticker top surface, to a defined stickerback subfile.

I didn't know him, in fact it seems to do what I do manually. When I need it, I'll try to use it and see if there are any differences.
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RE: About size of flattened sticker and formed sticker
#20
(2026-01-23, 7:59)Philippe Hurbain Wrote: I maintain that the dimension match between flat and formed stickers can be pretty loose, 1 or 2 Ldu over 40 ldu size is completely unnoticeable. Another consideration is that only the formed sticker size must be reasonnably precise to fit the part it's applied to. But flat version is essentially used for bill of materials so the needed dimension precision is pretty low.

And then you return to my initial idea (first post).
it is useless to match the size of the flattened sticker with its description.

Rather we make the folded version well and accurately.
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RE: About size of flattened sticker and formed sticker
#21
It looks like Massimo and I agree.

I think the flat version is the "single source of truth" in that it's the only state in which the sticker dimension can be measured. The formed version should follow from the flat. This is the only way that we maintain consistency in measurements and prevent file bloat.  However, once we've "locked in" (read made official) the files for a particular sticker size,  follow on stickers should be modeled to match.

Also, once again, 3dp is fine for flat. 5dp is fine for formed to match the vertexes of the curved surface.
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RE: About size of flattened sticker and formed sticker
#22
Ok. So Massimo PM'd me to state that he feels the "single source of truth" is the formed sticker. 

I disagree as I'm not sure how you measure the dimensions of a formed sticker and then flatten it and expect it to match the real world.

I think we're at an impasse and I want more input before I make a final determination.
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RE: About size of flattened sticker and formed sticker
#23
I take Massimo's point about the formed sticker being the "definitive" state which represents the true intended use case.

However, stickers are shipped flat on sheets, so a person modeling from the real-life part is going to use this as a basis; furthermore, I agree that this is the only form in which the real dimensions can be accurately measured. Also, when authoring the sticker pattern from a reference image, the best reference images are always going to be of the sticker in its flat form. So this should be the state from which its real physical characteristics (its size, the content of its pattern, etc.) are modeled.

With that being the case, I think any pending regulations on the size of stickers should account for the current proposal that LDraw code be added to the texmap functionality, because the manner of projection from flat to formed will surely have an impact on the relationship between the two geometries.

I also think the decision should be informed by how the tools that are currently in use, such as Pattern Folder, actually accomplish projecting the pattern and building up the stickerback thickness.

There is also the possibility that a texture might be projected onto surfaces of varying sizes depending on user settings, such as primitive substitution, and so the dimensions of a formed sticker part may indeed be variable.

In other words, I don't think any specification should exist regarding the size relationship between flat and formed stickers (and I don't think one is proposed), if that contravenes the result obtained by the actual utilities that carry out the spec.
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RE: About size of flattened sticker and formed sticker
#24
(2026-01-23, 22:18)N. W. Perry Wrote: I take Massimo's point about the formed sticker being the "definitive" state which represents the true intended use case.

I wouldnt say that's the only "true" way to see it.

While modern sets stray away from the idea, in the past there were a few examples of stickers being used on totally different parts for a B-model (which sometimes meant a sticker was applied both flat and formed).

Also, there are a few stickers (logos and such) where one might opt in for the idea of applying it randomly somewhere else.
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RE: About size of flattened sticker and formed sticker
#25
The only correct source for the sticker is the flat version:

* You design the flat version with the formed part underneath as template (counting in the 0.25 LDU for the stickerback) for your splits.
* Split and sub and rejoin them for the formed sticker.
* There is no need to remeasure the formed sticker, as it is based on the flat version we know is correct.

https://library.ldraw.org/parts/25778 has been done this way.

w.
LEGO ergo sum
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