Billboard design (very large)

Hello everyone,

I've got an employment from a transport company recently. My mission is to create three large billboards that they will be using on a fair. The measurements of these billboards have to be 5 x 2,5 meters (about 197 inches x 98 inches) each. Every billboard has to be the same size. The big deal is that a very large picture of a motorbike has to be all over the billboard. That means that the picture will need to be scaled up to 5 x 2,5 (sorry, I'm Dutch and we rather use meters than inches here in The Netherlands). My question to you is: How should I make this design in Adobe Illustrator? I was thinking of just making a new project of 5 x 2,5 meters, but elsewhere on the internet I've read that some people design the billboard at half the size of what the final print will become. For example: I'm working in a 2,5 x 1,25 meters project in Illustrator at 150 dpi (this project is 50% the size of the final print). When the design is taken to the printer, it will be scaled up to 100% (correct me if I'm wrong). That means that the measurements will now be 5 x 2,5 meters at half the dpi (75).

I've also been reading about vector images, which is what I'm going to use for the company logo to scale it up. But now, how will the 8,2MP (Canon EOS 30D) image look when I simply scale it up in Illustrator to the needed size? And is it just as simple as scaling the image up in Illustrator or will I have to do something else with the image before simply scaling it up in Illustrator? I'm not very familiar with printing photographs at a very large size, so perhaps someone could give me an advice on that.

It is by the way worth noticing that the three billboards will be in an exhibition, which means that the people that walk by will see the billboards at a relatively close distance. Now, of course, the billboards don't have to look extremely sharp, but it has to be just a pleasance to watch. Could one of you give me an advice of what dpi I should use for these measurements? Somewhere in the internet I've read that large city billboards often don't use a pixel density of more than 20 dpi (because of very large file sizes?), but I don't really know what would be a good dpi for these measurements (again: 5 x 2,5 meters or 197 inches x 98 inches).

I would really appreciate a fast and clear reply, because the job has to be done in just three weeks.

Thank you very much in advance!

Kees Braam,
The Netherlands

Jaffa Cake said:

Not quite the same thing, but if I'm working on something large – say an exhibition stand or banner – I'll do the artwork at a quarter size and 300dpi. It's then output at full size at 72dpi. Vector images aren't a problem of course, and bitmap images generally do okay, especially as they're usually seen from a bit of a distance.

What I'd do in this instance is have a chat with whoever is outputting the billboards, and see what they expect in terms of artwork.

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Yes, I was thinking of contacting the printer as well. But do you have any idea of what an 8,2MP image will look at that size?

And by the way: Thanks for you very quick reply!

panoz7 said:

The 30d outputs an image 3504 pixels wide. Divide that by the width of your banner (197") and you get a 17.8 pixels / inch PPI.

I found this formula that gives a rough idea of what PPI is needed given distance:

PPI = 1/((distance x .0001455)

Solving for distance gives this formula:

D = 1/(PPI x .0001455)

Using that formula and a 17.8 PPI you get a viewing distance of ~386" or ~9.8M

With a viewing distance under that you'll theoretically need a higher PPI image. That's not necessarily true though; a lot is going to depend on the type of the image, how much of the banner it fills, whatever treatment you give the image, and your viewer's expectations. A static photo of the motor bike would have very different requirements than a photo of the same motor bike on the track where the background will be blurred and nothing will be expected to be completely sharp.

You should also take your viewers expectations into account. Are these banners merely decorative or will the viewers be looking for details? The material that it's printed on will also have an affect. My guess is that even with relatively close viewing distances you'll still be able to get away with a fairly low PPI as long as the type and logos are sharp. People won't expect a very large photo on a banner to be as sharp as a museum print.

Your best bet is to print a letter sized crop of the image at it's final size. Look at it from your desired viewing distance and see if the resolution is appropriate. If that size isn't big enough to make an accurate judgement tile out part of it.

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Well, these banners will be merely decorative. Look at it this way: at the motor exhibition there is a space for each company. These spaces are simple squares placed next to each other. The idea is to place a billboard/banner at each side of the square room (left and right) and one at the back. The front is of course the entrance. Given this means that people will look at the billboards at a relatively close distance. The photographs that will be used do not contain much detail. The photos contain a subject with not too much detail around it, so in that case I really agree with you on the sharpness aspect. Because the viewing distance will be closer than 10 meters, it simply means that the dpi will need to be higher, am I right? What about 50 dpi? Will that give the viewer a nice image to look at?

Thanks for the reply.