A very large company has asked me for a large render of our Toon Santa character for display in an airport - they need 24" x 24" at 300 dpi, which if I am calculating right is 7200 x 7200.

Poser 7 just dies during rendering.

Poser Pro 2010 puts up its starting dialogs...then just sort of forgets what it is doing.

Is this size achievable in Poser? The best Ive been able to get so far is 3000 x 3000.

I believe 3000x3000 is the largest. But if its meant to be printed for a poster you only need 1200x1200 for the printer to read it correctly and print it without flaws. (talking about the company you choose to print this poster of Santa). But I've heard you can get larger renders. But I think it has to do with the type of rig your running not sure if its true or not.

300 ppi is probably more than is required for a large poster, but I've rendered larger than 7200 pixels in PP2010 with no problems, albeit with long render times.

I'd think in terms of 150 ppi - 200 ppi for a poster (3600x3600 - 4800x4800) but as suggested, confer with your printer, as "300dpi" tends to get specified - because it's the easy answer - when it's really not needed.

A cheat would be to render at 200 ppi, then interpolate in Photoshop to 300 ppi and apply some very subtle sharpening (smart sharpen rather than USM). It will be very difficult to spot the difference between this and a genuine 300 ppi render unless your nose is almost touching the poster. (More here).

Large renders will max out your RAM and CPU usage and make your PC unresponsive, which can look like it's just doing nothing or has hung. I'd use PP2010's queue and leave it to run overnight. 

I routinely render at 5120x1600 pixels, for use as desktop backgrounds on dual 2560x1600 pixel monitors.  I don't know of any arbitrary pixel limit in Poser.  I suspect that what your problem is not a limitation of Poser but rather that you are reaching the RAM limit of your machine.  The total render burden could roughly be described as RAM needed = {scene complexity}x{material sophistication}x{render quality settings}x{pixel dimensions}.

Poser 8, being limited to a 32bit RAM allocation -even on a 64bit machine- would hit the wall long before Poser Pro 2010, which can exploit as much RAM as your machine holds.

Big Poser Pro 2010 render used as desktop background:

Cspear's  suggestion should work - I've had stuff printed at much less than 300dpi and it looked fine. 

Chikako, if your pz3 has only content which you can redistribute (or which I already have), I'd be willing to have Cameron take a crack at the render.  She has dual hex processors and 96Gb of RAM.

I regularly do 8 x 10 @ 300 ppi so thats  2400 x 3000 in Poser.

I did a 36" X 24" Poster but that was 120 ppi.

If I did the arithmetic right 7200 x 7200 at 24 bit color and 300 ppi works out to 155 megabytes of memory to store the image. If your system is low on physical memory the application will crash.

Waht system are you running on ?

I had never done such a large render before, I usually stop at 3000x2000 which is sufficient for what I am doing. So as a test I did a render of  the scene I was working with at 7200x7200. This took a long time, but it worked.

The render at 800x800 took about 5 minutes. At 7200x7200 it took 4.5 hours. This is with PoserPro 2010 64, Windows 7 64 on a quad core machine with 8GB memory. Memory usage for FFRender64 was 600MB for the 800x800 render and 4.5GB for the 7200x7200 render. So I don't think it will render that size on a 32bit OS.

The scene was rendered with IDL, bucketsize at 32 and separate process active (4 threads)

If you are talking the file size of uncompressed RGB (which is what it would be in memory) then a 7200x7200x24 image comes out needing about 1186.5Mb.  To get the proper file size of an uncompressed image it is the Height * Width * Bit Depth (not color channel as so many inacurate websources say). Each Bit depth represents 1 more on off switch for that pixel and 1 more bit of data, it adds up exponentially for larger images.  I have saved 8.5x11 inch scans at 300 dpi and had them take over 150MBs easily.

I was talking how much memory Poser used when rendering these images. I was not talking about filesize.

Right, while in memory the image would essentially be uncompressed. In addition to the base memory of the actual image, there's overhead for the Poser program, the Objects, textures, and shadowmaps/raytrace vectors that use up memory in addition to that.  If you are on a 32 bit machine, rendering a very complicated scene, then your total memory usage can not excede 2Gb, and when it does Poser will begin behaving oddly, or crash outright.