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USGS pattern 17

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#1
Adam Wilbert

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You know you're in it deep when a simple pattern fill is keeping you up nights!

I'm having a heck of a time trying to find out some information on a particular pattern fill that USGS uses for mud / dry lakes etc. It's USGS #17 and has a very organic feeling spiral pattern of dots, maybe at 20-30% coverage:

Attached File  usgs17.gif   9.27KB   97 downloads
Attached File  usgssample.gif   203.24KB   89 downloads

How can I reproduce this in Illustrator? Does anyone have a pattern swatch to share? The pattern almost feels hand made, and not a simple mechanical fill. Is it? How does USGS reproduce it? Is there some underlying geometry, or is it truly random? The closest thing that I can find is a discussion of phyllotactic spirals (think sunflower seeds) and there is a circle generator available for Illustrator via Scriptographer. (see also a discussion on Fermat's spiral on Wikipedia)

Attached File  phyllotacticSpiral.png   104.66KB   72 downloads

...but trying to make a repeating pattern fill that retains the organic feel, the correct spacing, and is relatively seamless, is proving to be exceedingly difficult. Any insight, thoughts, or suggestions for further research would be appreciated.

Adam Wilbert

@awilbert
CartoGaia.com
Lynda.com author of "ArcGIS Essential Training"


#2
Anton van Tetering

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Hello Adam,

The sand symbol looks to me a bit like the sand-pattern used by the National Park Service.
At: http://www.nps.gov/h...ap-symbols.htm you can download map patterns for illustrator.
Anton van Tetering

Studio Haverstraat maps and panoramic photography
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#3
aug_aug

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Have you seen this?

FGDC Digital Cartographic Standard for Geologic Map Symbolization (PostScript Implementation)

I'm fairly sure your pattern should be in there...these are available as pdf/illustrator files.

#4
Adam Wilbert

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Hey, thanks for the links!

Anton, the NPS one is interesting if you look at it closely, they're not quite round dots, they're kind of ovoid shaped. And it doesn't quite tile seamlessly, it's just a hair off at the edges which makes little smiley faces if you zoom way in. Maybe that's supposed to be an intentional Park Service easter egg that all the folks at Harpers Ferry secretly snicker about! :)

Aug_aug, I actually referred someone else to that exact link recently, but had only ever downloaded the PDF files. And those only have examples of the pattern, not actual tile-able swatches. So thanks for pointing me back there. The AI files are exactly what I was looking for and I passed right over it. And what a treasure trove!

I'm always amazed at how such a subtle little change can have such a big impact on a project. Take a look at the before and after images below, the before being just a simple gridded 10% halftone dot, and the after being the more organic looking pattern at roughly the same density.

Attached File  before.jpg   169.74KB   85 downloads
before

Attached File  after.jpg   182.29KB   78 downloads
after

Thanks guys!

Adam Wilbert

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CartoGaia.com
Lynda.com author of "ArcGIS Essential Training"


#5
ravells

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Lol, I thought this was going to be easy...(famous last words) I think I've got there, almost.

The design definitely has an organic feel to it and there is some sort of underlying swirly pattern, but it's none of the more common dithering options I've come across. I've got a PS plug-in called 'India Ink' which makes dithering type patterns and hatches but it didn't have this one.

It also doesn't seem to be a pattern of pure black circular dots (not sure if that's a resolution issue on the image you posted), but some of the 'dots' don't appear circular and there is anti-aliasing in the image.

So, I took the image into 'imagesynth' which is a texture making plug-in for photoshop. That gave me a 512 tiling image which I saved out as a .png (see below). I then autotraced the .png in Serif Drawplus (an illustrator alternative) and saved the result as an SVG. It will work if the 'dots' are small, but at large sizes you'll see the different shapes and it breaks down....keeps the 'swirly' pattern though and at smaller sizes gives a variation of dot size without using antialiasing.

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#6
ravells

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SVG attached in zip format.

Attached Files


Create beautiful fantasy maps at the Cartographers' Guild
 

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