3D - Schme-Dee

Okay, this is rather an involved issue, so if you bore quickly then move on now and don't say I didn't warn you.

A few months ago the sales manger came to me and asked if I could create 3D models of some of the products to use in their sales catalog. I made a rendering with some pretty cool effects and they went gaga over it. Asked me to proceed with all haste making more of them. So I did.

And now here we are at the deadline for publishing and they are saying stuff like, "Get rid of the concrete and any flooring." Well most of you know that if you take away whatever it is that the lights are bouncing off of, everything changes. Ok, so I got past that part and then they said, "We need the background to be all white." Well, if you use a white background in AutoCAD you end up with a much different end result. Ok, so I got past that one slightly and then they said, "Put a drop shadow on it." That probable can be done in AutoCAD but it's not easy I'm sure and there are other tools for this like GIMP or PhotoShop. Ok, so I finally got past that and had some really realistic, photo quality renderings with drop shadows. Then the bomb dropped, "The shadows look like boxes and it's confusing....!" OK, now this is becoming something which I could do in a few hours and they are now turning it into days long events until I get the cookie cutter part of it down. Ok, I finally got over this too but here's the question for the group. Please note that I don't expect too many people to be able to answer or even recognize this as a problem, so extra credit will be given for accurate information.

When I first open any drawing on my system, the SUNPROPERTIES seems to default to 3:00 PM on Sep 21, 20xx of the current year. Okay, cool that's the first day of Fall, the Autumnal Exuinox, the whatever...but of course a time and day when the sun has some certain properties about it. When I rendered the image using a background, (see above they hated the sun&sky background in AutoCAD) I then saved the file to a jpeg. I then used GIMP to open the file and using the Fuzzy Selection Tool I grabbed all the background on the outside of the image, and then grabbed the rest of the background pixels inside the image (which is a hollow). I then deleted the selection while using a white background and viola...I had a beautiful image of my rendering on a perfectly white background. Added the drop shadow and it's a done deal.

The sales manager then said he didn't like the way the shadows (not the drop shadow) were being cast, made it look like there were boxes inside the image. Well on a mechanical part with straight edges all over it, that makes sense that the shadows cast were also made up of straight lines. So, I tried rotating the objects in the model space but that did not help. I then changed the date of the sun properties and this caused the shadows to look different like he was asking and it then looked like I was on my way to another resolution. But this time when I pulled the jpeg into GIMP and tried to select the background color it would grab areas inside of and on the surfaces in the objects as well. I can only assume that was due to the background color being reflected onto the surfaces of the objects in AutoCAD. This then totally screwed up the method of using GIMP to select just the background pixels. And it was making a sloppy mess with thousands of colored in pixels being left in the drawing which would have to be modified to clean it up, if you could even do that.

So, can anyone explain this? Is it just something one has to live with or is there some work around for this?

Oh yes, I tweaked around with the anti-aliasing, threshold setting for selecting in GIMP and it just would never work like it would if I rendered in AutoCAD with the sun set at 3:00 PM on Sep 21, 20xx.

Why not use a Light instead of the Sun as a means of casting light and shadows? Much easier control, that's for sure. And be sure to use Soft Shadows in the Advanced Rendering dialog so the shadow has a gradient falloff effect, and not the ray-traced hard edged shadows. I have some tutorials roaming around here somewhere on that....

http://www.cadtutor.net/tutorials/autocad/all-about-shadows.php I think you can find the settings if you select the light then go to properties>render shadow detail, and the same for sun properties, except you can only control the softness, there is no sharp option. If the edges are straight maybe you could just crop it with selection boxes (sorry if this doesn't work in GIMP I use PS) or use a blur tool.

You can also select an object go into properties and under 3d visualization set shadow display to "ignore shadows' , 'cast shadows' , 'cast and receive shadows' or 'receives shadows' for individual objects, but not individual faces, you can work around by getting tricky with slice or adding surfaces..

I think the company took the wrong approach. They should have hired a professional photographer who specializes in industrial/product photography. You've done an admirable job trying to keep up with the ever changing expectations of your boss. This really sounds like a case of "don't give me what I ask for, give me what I need". Unfortunately you are neither a mind reader nor a magician.

Why not use a Light instead of the Sun as a means of casting light and shadows? Much easier control, that's for sure. And be sure to use Soft Shadows in the Advanced Rendering dialog so the shadow has a gradient falloff effect, and not the ray-traced hard edged shadows. I have some tutorials roaming around here somewhere on that....

Agreed. If you're doing product shots, you don't want to use outdoor lighting. You should use a 3 point studio lighting set up with a key light, fill light and rim light. Something like this: http://3drender.com/light/3point.html

Thanks everyone. I'm reading that article on lighting now. And ReMark, yes I agree with you. The sales manager and I are friends and he asked me to do this. The first samples I gave him he said were great...then as we approach the deadline, he now changes the spec on me. Oh well, I just try to please.

http://3drender.com/light/3point.html

i learned more about lighting from that site than I did when I read a whole chapter about lighting in a book.

Put me down too as a steep learning on that link that CAD64 placed. Even though the docs said this is not the only way, in fact, they even said that it's kind of a dated process for lighting a scene...the heck with that it works pretty good. And for the first time I'm actually able to use no sunshine whatsoever to light this item. Now, as for getting it all like the sales manager wants it...that's what I'll be working on the rest of the night.

Still having trouble getting that white background going. If I shoot for a white background inside of AutoCAD the surfaces of the metal reflect too much white and it ruins the render. So I get great results when using something like 200,200,200 for a background choice. I save the rendering to a jpg and then use GIMP to open and edit it. But no matter what I try I cannot get the Fuzzy Selection tool to get the pixels properly and the edges of the object look like speckled paint have been sprayed along it...no good.

This is only when using this 3Point lighting technique. So is there some way to get use a white background but not have it illuminate anything in the scene? I found that by using a black background it got a little closer but even still GIMP would always leave trash pixels around the edges of the object which made it really look amateurish. I want to achieve this same effect but with a white background instead of white.

You should create a simple backdrop, similar to what's shown in the image below.

Thanks Cad64. I saw a very similar topic in one of my searches and I even tries this. Didn't get too much luck with it but I didn't get to test it very much. Will try some more with it today.

Like the Downing Effect I use Photoshop not GIMP so don't know that this will work but would be very surprised if it didn't.

Investigate using layers and masking rather than cutting out your image and pasting it onto a background. This will allow you to more easily fine-tune what you keep and don't from your image.

This link is a short tutorial which should help you.

dJE

Thanks. Here is what I've found works pretty good so far. Depending on the image I run the render with either a gray or black background. Then by setting the threshold in GIMP a little higher, I get the pixels I want and delete them so I end up with a pretty decent white background. Then I invert the selection and add a drop shadow. This is about as good as it's going to get. Now I need to figure out how to handle that saw-tooth affect that happens on the left door panel.

And does anyone know where I can get a better material sample for the aluminum diamond plate. I'm using steel diamond plate and it just doesn't have that shiny, aluminum finish I'm looking for.

Thanks. Here is what I've found works pretty good so far. Depending on the image I run the render with either a gray or black background. Then by setting the threshold in GIMP a little higher, I get the pixels I want and delete them so I end up with a pretty decent white background. Then I invert the selection and add a drop shadow. This is about as good as it's going to get. Now I need to figure out how to handle that saw-tooth affect that happens on the left door panel.

Are you saving your renders as jpg's? If so, don't. I don't know what formats Autocad can save to, but if you can, render and save as a high resolution tiff. That should give you a cleaner edge without such a bad stair stepping effect like you're getting now. Your render times will increase with the higher resolution though.