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AdamAvenali
04-20-2005, 09:06 PM
alright i read a couple threads i could find on this, but i'm still in the dark..

i'm doing a render for a graphic design project, so it will be going to print.. so i'm looking for 300 dpi..

the print size is 36 x 20"

i think lightwave only renders out at 72 dpi.. so i've come up with that i need to render around 7800 x 4400 so that i have ample room to resize this down and not lose any quality..

am i thinking right here? i took each dimension and multiplied it by 72 and then again by 3..

example: 36" x 72 dpi = 2592 pixels x 3 (so its three times the size i need) = 7776 pixels..

so what i'm asking, is there any thing that i should know before i start this render? am i thinking clearly? is there a way to change the dpi setting? how effective is the resample save feature? and how clearly does it keep the render?

thanks to anyone that can help me out..
adam

kmscottmoore
04-20-2005, 09:54 PM
Seduce,

Lightwave does NOT render at 72 dpi. It renders at the pixel by pixel dimensions that you specify. If you load the image into Photoshop, it will default to a 72 dpi count, but this is misleading. See this post:
http://vbulletin.newtek.com/showthread.php?s=&threadid=24297

If you want 36 x 20 at 300 dpi, then your image would be 10800 x 6000. The bad news is that Lightwave's max resolution is 8000 x 8000. The good news is that at 36 x 20, 300dpi is probably not necessary. As I explained in the linked post, the larger the image, the farther away that you will view it from, therefore resolution requirements go down.

I'm hazarding a guess here, but you will most likely be printing this image on a large format inkjet printer. In spite of claims and advertisments by the manufacturers of these devices, their true resolution is around 85 lpi. So, your target resolution should be around 130 dpi. 36 x 20 at 130 dpi yields an image resolution of 4680 x 2600. This is within Lightwave's capabilities, but it will require a lot of RAM.

AdamAvenali
04-20-2005, 10:24 PM
thanks for the quick reply and the relieving information! i'm gonna give it a try! thanks again :)

ingo
04-21-2005, 02:15 AM
.......The bad news is that Lightwave's max resolution is 8000 x 8000. The good news is that at 36 x 20, 300dpi is probably not necessary. .......


Me thinks you're a bit wrong. If Lightwave has any maximum resolution it will be 16000x16000. I had no problem rendering at 12000x7500 and other resolutions above you're mentioned maximum resolution.

Weetos
04-21-2005, 05:50 AM
as much RAM is required for large format, you might want to use splitrender, which basically splits your render into tiles (which renders much faster and require less RAM). I can't tell wher you can get it, but I guess it's available on flay.com

Hope that helps

kmscottmoore
04-21-2005, 07:24 AM
Ingo,

You got me.
Lightwave's max is 16000 x 16000. But, I think that this was increased in version 8 from the previous 8000 pixel limit.

Dave Jerrard
04-22-2005, 06:47 PM
alright i read a couple threads i could find on this, but i'm still in the dark..

i'm doing a render for a graphic design project, so it will be going to print.. so i'm looking for 300 dpi..

the print size is 36 x 20"

i think lightwave only renders out at 72 dpi..

No it doesn't. LightWave renders X pixels by Y pixels. DPI is HARDWARE specific value for things like printers, scanners, and occasionally monitors (like Macs or fixed pixel displays, which are often labeled using Pixels Per Inch) . An image has NO DPI value whatsoever. It does have a PPI value, but ONLY when it's being output. Adobe has really misguided people about this when they started using DPI values in image files. First, that should be PPI since an image isn't hardware. You can zoom in & out of it all you want, and that is actually changing the pixels per inch that you're viewing. The monitor you're viewing it on also has an effect onthe Pixel Per Inch. Remember I said it only has aPPI when it's being output? A monitor is an output device. So, if I have a mac monitor, and I'm viewing the image at 100%, I'm seeing it at 72PPI, because that's what MAc monitors are physically set to (their cinema screens might be different). If I view it on my LCD monitor, I'm seeing 100PPI because that's the physical resolutioin of my monitor. If I hook up a projector to my other video output and project the same image onto a whall, what am I getting? Depends on how far the wall is. PPI is entirely depended on output size.

LightWave doesn't save DPI information because it's pointless. The 72DPI come up because Adobe, in their misguided wisdom, decided that if they can't find a DPI calue, they'll just make one up, and they based it on the Mac displays many years ago. They stuck it in there to "make it easier" for people to understand what PIXEL resolutions they needed for different output, without having to actually figure it out themselves, like you're doing now.


so i've come up with that i need to render around 7800 x 4400 so that i have ample room to resize this down and not lose any quality..

am i thinking right here? i took each dimension and multiplied it by 72 and then again by 3..

example: 36" x 72 dpi = 2592 pixels x 3 (so its three times the size i need) = 7776 pixels..

so what i'm asking, is there any thing that i should know before i start this render? am i thinking clearly? is there a way to change the dpi setting? how effective is the resample save feature? and how clearly does it keep the render?

Ok, you're not far off! The first thing you should be aware of is how the poster is going to be printed. Find this out as early as you can. Is it going to be halftoned for offset printing (like magazines, newspapers and posters), or is it going through a large format printer (which could be thermal wax transfer, inkjet, dye sublimation, laser, etc.). If it's halftone, chances are that it's going to be a 100 to 133 line screen. This means, an array of dots is used (look at a newspaper photograph and you'll see these dots) that has 100 - 133 lines of dots per inch. This is shorted to Lines per inch (LPI) or just lines, like a 133 line screen.

A rule of thumb (a GUIDELINE - this is not set in stone anywhere) is that output resolution (that PPI I just covered) should be double the LPI. Generally anything higher would be lost in the screening process. Most magazines use a 133 line screen. Higher quality print runs, like brochures, and some photographic magazines, use a 150 line screen. This is where you get the rule of thumb that photographs should be 300 DPI (they should say PPI :). But these are viewed close up and have to stand up to a higher level of inspection than a poster that's normally viewed from a few feet away.

Now, assuming this is going to be screened at 133 lines, if we double that value, we get 266. There's your output resolution. 266 PPI. 36" X 266 = 8512 pixels. That will make a really sharp poster. A 100 line screen makes it even easier. 100 lines times 2 = 200 PPI, times 36" = 6400 pixels. The value you came up with fits right in that range!

Now there's no rule that says you have to have at least 200 PPI for a poster. I've done some at 100 PPI and lower, and they turned out great. Unless you're looking at it with your nose inches away, you won't be able to tell. Stand back about five feet from your monitor and try to pick out the pixels. Your monitor is probably displaying between 72 and 100 pixels per inch.

Now I'm not exactly sure why you're multiplying 72 by 3. Is this just to have room to scale down? If so, that's overkill. Just render about 5-10% larger than you need. This usually gives you enough room for cropping and scaling.

I posted a bigger message about this on CGTalk, and you can find the thread here:
http://www.cgtalk.com/showthread.php?t=221155
And another one on the NewTek forums, here:
http://vbulletin.newtek.com/showthread.php?p=267146#post267146

He Who Really Thinks He Should Write A Full Page About This.