Never have done this before.....

I have been working on a theme of 3D images and have been rendering the individual images to 1440 x 1080.  They are approx. 16 x 19 inches as measured in photoshop.  They are sized for art competition.  When jpeged down... they run about 320kb.  if you care to see them.... they are at photobucket under my screen name Deepsees. 

Are these images suited for submission as they currently measure?

Deepsees

Wouldn't that depend on the submission requirements for where you are submitting?  BTW, "16 x 19 inches" means nothing when submitting.  It is all about pixel size.

I usually render out images at 3000x3000. It's large enough for most sites. I'd suggest rerendering your images at a larger size.

Thanks for the information.  As I stated, I rendered these images to 1440 x 1080 (based on HDTV display) which generated a certain image size for going to print from PS.

I can render to any size.  Normally my res is 300 dpi on anything that I expect to print.  With that said, shouldn't I be able to increase image size by going to 72 dpi?

No. If you print at 72 dpi you will get a bigger print than if you print at 300 dpi (for the same number of pixels), but that doesn't make the pixel dimensions any bigger. Forget dpi for digital files (unless you're actually printing them).

You are using textures not big enought in your renders even at the size you rendered, so forget render them at biger size.
You should always use big enough textures to the size you are going to output the render, otherwise it will shaow the pixelation as happened in these cases.

Deepsees, what site or sites did you want to submit to?
You've never said exactly what you hope to do with your work.

Most of the images were rendered to 72 because they were to go on a fishing web site and were not intended to go to print.

Stop discussing dpi (72).  That is irrelevant to submitting to stock sites.  Discuss pixel resolution instead 1440x1080.

1440 x 1080 is the pixel dimension.
I came from a print background and was a bit confused at first about using pixels instead of inches and dpi.

I was under the impression that 1440 x 1080 was pixel resolution.  Apparently confusing that with dpi.  I don't mean to stink up the place.  Thanks.

Yes, it is, but you keep mentioning the dpi(72) as well.  You don't need to concern yourself for that in this area.

You will be learning also a lot by looking at 3D rendered images at any give stock image site you can see on the right hands side of this forum.

Check Istockphoto, Shutterstock and Dreamstime to see what your "competition" is doing and how good the quality is.

If you want to produce stock material rendered on your computer, you need to meet certain criteria to make it worthwhile.
First you need to develop an eye for what is considered "stock". Once you get some concepts together of what you can render you need to meet the file requirements to be even considered for an application.

The bigger the file size the better. I have 3D renders over 6000x6000 pixels or 12 MB in file size. Some of those took me over 24 hours to render on a Quad Core PC with 4GB of RAM which is almost considered a joke by now.

I'm also taking photos so I don't have to rely on producing only one image a day!

The more realistic your image looks like (realistic lighting) the longer your computer will take to render it nicely. Many times people who can model objects nicely forget about the importance of proper lighting to make it look perfect.

You will see the most successful 3D renders on Istock which have been approved lately are of very high quality. That should be your goal. There are a lot of people out there doing the same thing so it's a tough competition. You need to stand out in order to be successful.

So study your field, render very high resolution and make sure you get the lighting right!

Good luck!

Thanks  Click.... I am no stranger to 3D...  I have been doing 3d sculpting and animation for thirteen years and some of my single-image- to-print files are 200 mb+  I have been using Strata products for the past three upgrades.  My longest animation is two minutes that took nearly two years to render using a Mac 7100...

Don't forget that in this business you have to upload new images constantly. The more you upload (the more you can render) the better.
I'm only investing so much time into some renders because I know from experience that they will sell often enough to pay me back for the time.

Other really successful 3D artists are actually using 6 computers simultaneously to be able to produce enough content to stay competitive.
It's not far fetched to rent a render farm online for certain projects.

Good luck!