Sketchup, Pepakura, Inkscape, Gimp, et al...

Discussion in 'Gallery & Designs' started by bclemens, Feb 13, 2008.

  1. looker

    looker Member

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    Interesting way of doing things, leaving me with one question. What format do you use for exporting from the free version of sketchup into pepakura?
  2. bclemens

    bclemens Member

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    Export the Sketchup illustration as a Google Earth 4 .kmz file. Pepakura can open that.
  3. bclemens

    bclemens Member

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    Pepakura has vector graphics output.

    I just discovered that Pepakura can be set to output a vector graphic rather than a bitmap...this may help simplify the design process- more later...
  4. CJTK1701

    CJTK1701 Banned

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    bclemens, I'm watching everything you're doing and taking it all in. Thanks for sharing this information and thanks for starting this thread. Good to see another Missouri man on here. Go Mighty Mo!
  5. bclemens

    bclemens Member

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    More discoveries and an experiment

    Thanks, Cjtk1701...
    so, the vector output of Pepakura was not much help. Although you can use a vector development within Pepakura, the only export option you have is bitmap. The good news is that I had set my bitmap output on "medium" quality. Setting it on "very good" allowed me to increase the quality of the bitmap import into Inkscape to the point where I could use Inkscape's "Trace Bitmap" tool to convert the image into a vector object. I shouldn't need to manually trace the bitmaps anymore.

    The next problem was that when I imported the Pepakura bitmap into Inkscape, the scale changed. The imported bitmap was consistently about 80% of the original size. In order to determine the reason for this, I crafted an experiment this afternoon. I went back to the source, Sketchup, and built a cube that I scaled at exactly 1 inch on each side. I then exported it as a Google Earth 4 .kmz file. Opening it in Pepakura, and unfolding it, it filled the page. In the Pepakura 2-D view I had to specify a scale factor (Pepakura only uses centimeters- go figure ;)) I wanted the assembly to be 1 inch high so I put in 2.54 centimeters. It rescaled the development accordingly. I printed it out from Pepakura, and sure enough, it was a good 1 inch box. No problem here.

    Next I exported the development as a "very high" quality bitmap. Then I imported it into Inkscape, and immediately saw, from the scales on the border, that it was too small. I looked all over Inkscape for some sort of box or button to adjust import scale to 100% but there was nothing. Then I hit Google and found, in one of the Inkscape tutorials, the explanation. Inkscape imports based on the number of pixels per inch. Inkscape bases its scaling on a 90 Px/inch standard. If the program that does the exporting doesn't export at 90 Px/inch, the scale will be different. Pepakura exports at 72 Px/ inch. 72/90 = .8 Hence the bitmap comes into Inkscape at 80% of the size it needs to be.

    As of now, my solution is to go back to every Sketchup file I have created for the Yak and add a standard cube of exactly 1/2 inch on a side to the image.
    [​IMG]

    Then when I unfold it and export it from Pepakura into Inkscape, I can simply scale the imported bitmap so the cube development matches 1/2 inch on the Inkscape scale. Then I can trace the bitmap, separate the components, and delete the cube. Now at least all my parts are to scale and correct relative to each other.

    Whew! The learning curve just keeps on going!
    Cheers!
    Bruce
  6. CJTK1701

    CJTK1701 Banned

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    You can take a bitmap file into "Paint" and change it into .jpg, or .png, or .tiff. Also, I have an older version of Photoshop if you need any help, let me know.
  7. OhioMike

    OhioMike Member

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    bclemens...have you tried the un-folding tool for sketch-up yet???fhttp://sketchuptips.blogspot.com/2007/08/plugin-unfoldrb.html
  8. bclemens

    bclemens Member

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    Hi, OhioMike,
    Yes, I have tried the Sketchup unfolding tool. It has potential, but it is not as straightforward as Pepakura. For example, I created a simple "cigar" shape in Sketchup which consisted of several individual sections. It would have been similar to, say, a V1 fuselage.

    When I used Sketchup's unfolding tool on each segment, they all unfolded OK, but each one was in a different horizontal plane. I spent lots and lots of time trying to put them all together in a flat, horizontal image. Pepakura doesn't have that problem. I think my efforts to learn Pepakura will be better spent.
    Cheers,
    Bruce
  9. Lex

    Lex Dollmaker

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    Nice and interesting way of doing things! I wonder if Pepakura supports unfolding with textures done in Sketchup?
  10. CJTK1701

    CJTK1701 Banned

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    I've got to tell you again, I'm really eating this all up and taking it all in. I appreciate you do this tutorial.:thumb:

  11. bclemens

    bclemens Member

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    Things I've learned this week...

    Yes, Lex, Pepakura will allow you to place the same textures in the 2-d development that you used in Sketchup on the original model. Unfortunately, it is not an automatic process. When you import your model into Pepakura, it'll lose some or all of the textures you had assigned in Sketchup. After you unfold your model, you must then reassign the textures to the faces in the 2-D development using Pepakura's 3DModelWindow > Texture Configuration dialog. You'll be able to scroll through your various surfaces and assign any texture to that surface.

    When I did that today, I found that some of the faces had texture that was scaled differently than others. I was using a stucco texture with sand pebbles in it for a building. On some faces the sand was large, and on other faces it was small. I am not yet sure if this is an issue with Pepakura or with my original Sketchup model.

    Other things I learned:
    • Pepakura is not magic! Don't try to import a whole complicated model into Pepakura and expect it to unfold it well.
    [​IMG]
    • It will make a mess of it! What it creates may be a mathematically consistent development but there is no way to build it. Or, it may decide to put a seam straight through a face you want untouched. I found that it is best to split up my final model into small simple subassemblies and import and unfold them individually.
    [​IMG]
    • You will have to do some manual "tweaking" on your 2-D development. you'll have to beta-build it, reposition flaps, combine edges, separate edges, rotate things, and do lots of pesky picky things to make it buildable.
    • Pepakura doesn't care about scale. If you are importing various subassemblies as I mentioned above, Pepakura doesn't keep track of one development's size to match it to the next. And Pepakura doesn't have rulers on the side like most graphics programs. Yes, you can scale things up and down in Pepakura, but the scale is based on a simple percentage of the original size. The program just tries to fit the first 2-D development to whatever page size you have as default. So I have taken to keeping a "standard square" object that I create in Sketchup and import together with the model.
    [​IMG]
    • This square is for instance 1 inch on a side (In the example above I chose 2 1/2 inches a side so I could scale the model easily to 1/48"). Then, when Pepakura unfolds the model and I'm done cleaning it up, that 1 inch square follows the development along as I import it into other programs where I can scale it accurately. Tedious!!!
    • Finally, as I mentioned before, the output from Pepakura still needs to be imported into another program like Gimp, Photoshop, Adobe Illustrator, or Inkscape for the final scaling, merging, touchup, coloring, etc. At this point, it seems any textures, markings, colors, etc you applied in Sketchup have been rescaled, messed up, mixed up, lost, changed, and any number of other problems introduced. I think it would be best to simply work in black lines until this last part and after the .bmp from Pepakura has been imported, traced and vectorized, only then apply final colors and textures.
    Whew! As I said earlier in this thread, I really appreciate the monumental amount of work it takes to put out a high quality, good fitting, well designed, detailed paper model! There are no easy answers here and no inexpensive one-stop application that will let us become model designers overnight. The learning curve is very steep. Hey- someone hand me that rope- I think I may have found another foothold on this cliff!

    Cheers,
    Bruce
  12. RyanShort1

    RyanShort1 Member

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    One note about GIMP - you REALLY ought to learn to use the "Paths" features. The Paths are essentially vector-based.
    You can use Paths to create scaleable designs such as serial numbers, etc... They can also be used to select crisp areas to work on.
    That's what I used for the detail markings on the latest B-25 profile (of aircraft #16) on my website. At some point in the future, I could relatively easily created profiles of ALL of the aircraft.
    Basically, I think that almost everything done in Inkscape could be mimicked in GIMP.

    Ryan
  13. bclemens

    bclemens Member

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    Ryan,
    Thanks for posting! Great website and great work you are doing. This is one of those days when I am convinced things happen for a reason. I just discovered Paths in Gimp. And then you posted this response. This comes on top of my elderly father giving me an old book on card model design this afternoon:

    http://forum.zealot.com/t156973/

    and it looks like what you say is true-- if I can master Gimp paths I won't need Inkscape and that will reduce the model design overhead by 25%. I'll get working on it.

    I actually have a book on Gimp that I bought last year. Let's see...it's gotta be in one of these piles around here...oh well, if I can't find it I'll open the help file and go to Google- just like with everything else I'm trying to learn!

    Cheers!
    Bruce
  14. Lex

    Lex Dollmaker

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    Bruce:

    A few tips, in Pepakura there is an "Auto" checkbox beside the unfold button, uncheck that checkbox and it allows you to set the scale of the model ^^

    ...And I really agree on breaking the model down to subassemblies, especially if you found out that one of your surfaces is without texture and have to go back and edit the input model, go through the unfolding process again.........

    You can also specify edges to be cut before you unfold the model, so that Pepakura gets a better understanding of how the model is going to unfold :D

    PS: From my experience pepakura unfolds textures just fine, and that is what I do all times, since I fear adding textures in graphic software after unfolding might lead to texture mismatch between parts.
  15. bclemens

    bclemens Member

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    Thanks Lex! That helps... There are so many subtleties to learn- especially when you're trying to become proficient in several programs at once.

    One question, Lex,
    Say I have an object that I have textured in Sketchup, and I rescale the texture to suit the object. When I import the object into Pepakura and it loses the texture, I have to reassign the texture from the original bitmap. When I do that the texture comes in at the original scale, not the correct scale.
    Is there any way to rescale the texture in Pepakura? If not, I'll have to forget about textures until the final output in Gimp.

    Thanks,
    Bruce
  16. RyanShort1

    RyanShort1 Member

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    Well, I'm officially trying my hand in Sketchup. Couldn't resist, and it seems to work pretty nicely. I've also been finding some other tools that can be used in Sketchup - such as a plugin that allows one to use a Bezier curve.

    Here's a shot:

    [​IMG]

    Ryan
  17. Dragos

    Dragos Active Member

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    I'm using Scketchup, it's very easy , but I do not like using Pepakura Designer for unfolding
  18. OhioMike

    OhioMike Member

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    Their looking for "waybe" beta testers for Sketchup now iguess from what i read on this web site. Might make sketchup the end all be all?????Waybe - Home
  19. bclemens

    bclemens Member

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    I've been working a lot with Sketchup lately- I think I'm over the steepest part of the learning curve now... Yes, Ryan, the Bezier curves is a great plugin- indespensible.

    I decided to put the Yak on hold and work on something more geometrical. This will allow me to learn a lot about using sketchup as the first part of a model's development. Here's a cardboard sundial I have finished the preliminary design on:

    [​IMG]

    Now it's in to Pepakura, a piece at a time for unfolding, then on to Gimp for scaling and finish. So far the Gimp is the most difficult part of the puzzle for me- but there are a lot of good tutorials out there now.

    One really cool thing about Sketchup is the "Shadows" feature. It allows me to set the sun angle for any day of the year and any time of day. Once I determined Sketchup's solar declination by experiment, I was able to set the angle on the sundial arrow to match and voila, I could mark the sundial accurately. The display will be more elegant in the final stage, but for now there are 4 rows of marks, each row corresponds, from front to back, to Winter Solstice, Spring Equinox, Summer Solstice, and Fall Equinox. No matter what time of year it is, the sundial will be fairly close, as long as the arrow is set to the angle of the latitude of the location. The curved piece that goes through the stand is marked in 5 degree increments to allow that adjustment.

    The cap piece on the stand will be removable when one makes the angle adjustment, and then slide down the shaft to lock it in place.

    I agree, Dragos- Pepakura is clunky and obstinate- but is there something better out there?

    Cheers,
    Bruce
  20. Dragos

    Dragos Active Member

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    I don't know if there is something better , but I'm searching :mrgreen: