Eh, I'd say it's fine to do from an artistic standpoint if you have real trouble drawing a specific thing, but I guess what you're asking is if it's legal to use traced/heavily referenced images from sketchup? From what I know of the site I'd guess it's mostly okay, though there might be some creators who doesn't want their models to be traced? Maybe provide references for what you traced.
It's not the first time I hear about this. A lot of professional comic creator use this especially for difficult camera angles.
Check out Bearmageddon213 for which the creator uses this.
There's no shame in using tools available. We have so much to do, and so little time... And we do it for free!
I don't use it personally because I always draw on the go with the Ipad. Would be too much trouble importing files from one device to the other. I go quicker without. My architecture and proportions might be a little clunky as a result!
Oh wow, I totally didn't notice that from Dr. Frost!
Haha. Thank you very much for replying, and yeah, haha, I just get a bit paranoid when it comes to drawing stuff since half the time I feel like I'm totally doing something wrong. Though in the end, I guess so so long as it's acceptable then it's fine? 
I usually create the room from scratch but my main concern is the furniture and other tiny stuff? Like, I'm not too worried tracing from rooms that I created on my own, but when I add other small things like a table or a sofa I got from the 3d warehouse, I'm a bit worried that I might be doing something wrong by loading it into a room I made?
@Jrej
Ohhh, I'll be sure to check out that link then, thanks!
At best, the backgrounds I can draw usually involve square symmetrical rooms with barely any furniture in it. Which is pretty much why I decided to build rooms from scratch in sketchup since I felt like I'd be able to make a room that feels authentic vs the plain and empty ones I can make. I guess my main concern is that I was a bit confused by sketchup's TOS and I don't want to find out later on that what I was doing was bordering on tracing /plagiarizing?
You mean getting the wrong perspective? You might want to try this178, it's a 3D interior decorating tool where you can place things in a room and view it from many different perspectives.
I've seen sketchup models and photo refs being traced over in both amateur and professional comics. Sometimes the effect is a little jarring almost like characters are cut and pasted on the background but readers will only spend so much time on one panel anyways. I think it's fine so long as you can balance the look with your style of drawing .
If you're talking about copyrights and such, they come in to effect if you're intending to profit your comic. These are subject to the laws in your country but in general, as long as you change something like 25% of the original you're pretty safe from infringement. This is pretty common in the film industry to modify props like paintings they got at some flea market. Hire an artist to change it just enough, then they won't be sued when the movie comes out and it happens to be in one of the main scenes.
I had this fear myself. I dont use sketchup but I use poser ten for my comic backgrounds and some props. in the end use what you need to make your story as long as your not stealing ideas and artwork your not doing anything wrong.
@Zanreo WOW. Thank you so much for the link! This is incredibly helpful. 
@somvi Yeah. I was worried about the infringement thing, while I'm not looking to profit from my webcomic, I just don't really want to end up doing something that could border on infringement at this point. I'd feel bad haha. As long as it looks far from the original model then I'm fine?
@aronthemason Thanks! Sketchup's a bit intimidating to use since the TOS is pretty vague for me and I often wonder if what I'm doing is okay. At this point, I should really probably learn how to draw proper backgrounds.
Try to modify the scene to really make it "yours" wherever it makes sense. I mean, some things are pretty generic like standard sofas, tables and chairs so it's not such a big deal but, something more unique like a statue of armor would require much more effort.
Yes, there are a lot of pros that use these type of tools, I know about a top of the line mangaka that use that technique for creating complicated backgrounds, a 3d model that gets "traced" or copied to make it look more traditional, the result is amazing let me tell you.
A little bit out of topic, but some artists also use 3d models to get tricky perspective shots of their characters.
Others just use 3d rendered backgrounds for their webcomics, it's a common practice among some creators, so if you're into it, go ahead =] . I should advice on changing it a little as it was suggested here.
Many famous manga as Gantz, Rosario + Vampire and other uses 3d resources. It's a common pratice and the only ones who really complains about this are some "pseudo-artists". But no problem for readers.
^^I agree. Also, didn't Yuumei make some tutorial on how to do it on Deviantart? Lol there's no shame.
I think whatever tools and reference you need to use to get the best possible result are totally acceptable. I've seen some old school cartoonists call using sketchup "cheating" but honestly you have to build your environments before you can draw over them, which can take just as much if not more time.
One really important thing to keep in mind if you do use sketch-up, photo-ref or any other non-construction based method of creating environment: you still NEED TO UNDERSTAND the rules of perspective. Most importantly how to make all the other objects and/or character you add to the scene MATCH the perspective you have created. If you have a beautifully created background from sketch-up but nothing matches that perspective, it will look wrong in the uncanny valley kind of way.
My suggestion to remedy this is:
1. create you backgrounds in sketch-up first
2. bring them into your pencils
3. Find the vanishing points for the scene based on the background
4. create everything else using those vanishing points.
NOTE: this process works if you are using photo-ref as well
This way you can create those complex backgrounds in sketch-up and the rest of your scene will blend together seamlessly.
I make heavy use of a free open source modeling tool called Blender19 to plan out the backgrounds and scene layout. Since it has a built-in rendering system that some say could rival V-Ray and Maya, I can quickly get some good lighting reference too.
Here's an example of a panel I used Blender to help with light and perspective.
Oh yes! This so much!~I had to learn the hard way when first making backgrounds using manga studios 3D functions that if my characters weren't in perspective, it ruins the pages potential ;/ I use it all the time in my manga right now but here's something from a manga I'm making at the moment that I haven't shared anywhere yet.
Plus I also think that 3d models helps with consistency when moving the camera angles around the character. Sometimes i would forget to put a certain object somewhere in the background where it should be ;T
Oh hell yes, it's okay to use SketchUp and 3D models for perspective help. My team does that all the time, especially with background settings we're going to be using multiple times! While Alan, our background guy, is more than capable of doing perspective work, sometimes it's just too work intensive to lay all of that out AND stay on top of deadline. With SketchUp we're able to keep our characters in proper perspective, and/or shift the set if need be.
For example, Alan will model up a setting that we're going to be using a lot, like the Razor Compound here. This is just an overall shot of the model, but then...
We frame it to how we want our set up to look in the comic itself. This is a back alley section of the compound. Figuring out the layout etc would have been a nightmare without the model.
After this point, we take screen shots of the background and lay them into the artwork. This allows us to make any revisions to the clean art for perspective compensation. For some reason it's not allowing me to upload that. But srsly, it's just the above overlayed on top of the drawings.
From there the background is vectored out...
Then greyscaled...
Then we add color...
After that we texture the background, drop in the characters, add any color treatment to them, and put effects in too. So the final thing, without text, looks like this:
And the final page looks like this:
The other thing we LOVE SketchUp for is weapons and vehicles. We model everything ourselves based on designs that the team comes up with. From there we can use those models for just about anything. They're easy to pose, and when they're inked it looks hella awesome!
For example: Weapon of Choice
And this is one of the pages it was used really heavily on. The ATV thing (we call them Jerboa's) are all the same model, just thrown in where needed. You also see us reusing that Razor Compound model here too!
ahem TO RECAP:
Omg you're not cheating or less hardcore or whatever by cutting your work in half by using a TOOL. Have fun with it!
Thank you so much for taking the time to respond to this! Wow. I didn't think that a lot of people would actually respond to this. As someone really new to Tapastic, I was a bit unsure if someone would actually reply to this.
@somvi Thanks! I'll be sure to keep that in mind. 
@Menbung I usually do the former in which I trace the model I made since I feel like using a 3d rendered background clashes heavily with how I draw. But yeah, I guess as long as I change it to look as different as possible from the original model then its okay? Haha.
@toonsfera Oh wow, I didn't know that those manga uses 3d resources! I know that some webtoons do, but I wasn't aware that some manga did the same!
@blacknwhiteeagle100 I got the idea to use sketchup from Yuumei, but I guess I was just a bit worried because of how some artists get accused of tracing and stuff? Haha. But so far, it seems like it's totally okay to use sketchup!
@MrKyleRose Thank you so much for that piece of advice! I've also had a bit of that problem tbh, since when I add a person to the background it feels a bit wonky haha.
@SethJH I've actually heard of Blender but I got a bit intimidated since it looked very complex. So I chose sketchup instead because it looks relatively manageable for me. But wow, you're amazing! Those panels look really good.
@Tanisha Oh wow the panel looks amazing! I have the same problem too myself but I usually stick to simple background perspectives so that the perspective of the characters that need to be added to the scene aren't too complex haha. I guess I just have to practice lots if I want to do anything more complex.
@Kamikaze Woooooooooooooowwwwwwwww. Your models are just wow. That is amazing! And extremely helpful! Question though, after you guys screenshot the 'scene' do you still redraw the lineart? Or does the screenshot appear that clean already? Sorry, I' m super new when it comes to making my own backgrounds using sketchup.
Haha. I was honestly really worried about being accused of 'cheating' or 'tracing' and stuff by using sketchup for bgs tbh. Since I've seen a lot of artists receive a lot of flak because of that. But based on everyone's response, I've come to the conclusion that it's okay to use all the tools I can!
Let me chime in here as well.
I use DAZ 3D for both of the comics I do. One of them, Warmage11, is a straight up CGI comic that I do postwork on to give it a hand drawn art look. You can see the pencil and ink lines on it, even though a computer did all of it. I just do a little work with my tablet on it to do things that could not be done in the 3D programme.
But the other one is The Shadow War, and that's the one that I go all out on. I do the basic layouts and composition in DAZ, and then convert the shots to line drawings within DAZ. This is a sample of what that looks like:
From there, I print it out at 10"X15" and take it to the lightbox, and lay a comic board over it and start the inking. Now, inking is a lot more than tracing, as anyone who has done a lot of it will tell you. You are basically re-drawing everything on the paper, while at the same time giving line weight, cleaning up mistakes, and in this case, making alterations. That's a Han Solo blaster standing in for Mockingbird's Steinman, so the gun gets redrawn. That's an iPhone stuck to his arm, so that gets redrawn as the arm screen. Since I am only worried about layouts and perspective here, there are walls that are not even there in the lineart that have to be done in the inking. This is the inks on that page:
I'm doing ink washes as well as straight up inking on these. Now comes the fun part, the painting. Everything here is done with brush, and a little airbrushing for final touches. It's the part of the process I enjoy the most.
The final page has the last two panels reversed, as it helped the eye-flow better. There's a little digital work on the arm screen, and the lettering on the pistol, but the teleport effects were done with brush and airbrush.
Now, the nice thing about most DAZ models is that the standard license says you can do anything you want with them, free or commercial, as long as you don't try to re-sell or distribute the model itself. In other words, the creators expect you to use their models in your pictures. That's what they make them for.
Hope this helps a bit.
Eagle
(I only do digital/CGI for comics, but I love the new toys to play with!)
@enidean The screenshots look REALLY clean and they're easy to follow. Alan, our background guy, takes that screenshot and then traces vectors of it in illustrator. So it definitely has to be redrawn, and often Alan will add in further detail as well, like trash on the ground, or foreground framing elements etc. I'm really glad you found the screenshots helpful!
