Workflow from cad drawing to beauty render?

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Old 03 March 2007   #1
Workflow from cad drawing to beauty render?

I need to make and render a number of models which have technical drawing done in mostly autocad.
These drawings are all in dwg which blender doesn't seem to import. One file was available in dxf also, but it was an isometric view converted to a flat plane, which is kinda useless if you want a 3d object.

What I want to do is this:
1. import the side/top drawings in whatever format works.
2. preferably have the imported drawings as curves.
3. create a 3d image out of it
4. figure out a nice lighting rig that I can use to make beauty renders.
5. These renders WILL be for print, and a lot of them will have similar objects, so the lighting and color needs to be uniform.
6. what format best to use for these renders? I prefer something that can be cymk, since it is for print. it's for a LOT of things, so manually changing color curves afterwards isn't really doable. I have photoshop acces now, but I don't know what other filetypes support cymk. (how was this done for elephant's dream? surely they had uniform colors with all that stuff printed for it?)

problems I have now:
1. So far importing paths wont work. I've had acces to only one dxf file, which looks okay in object mode as a 2d curve, however it is a mesh with a gazilion vertex. NOT good.
unfortunately last week I couldnīt save some of these files in different types, They were finalised drawings and the guy that did them didnīt have priviliges to alter or resave them.
He could export them as illustrator .ai, svg and eps. Heīs been saving them as various types, none of these would open in blender. some wouldnīt import, others would crash blender.
or at least make it do nothing. Itīs probably since there are so many variation in VERSION of these filetypes but it still sucks. I could open some of these files exported out of autocad into illustrator cs2, and resave them as the lowest version available.
None of these versions will import.

2. The dxf I mentioned earlier was a mesh instead of a curve. when importing paths, Iīd rather have curves. howto do this?

3. I think I can handle that, I need the drawings first.

4. Lighting, kinda clueless here. Donīt know too much about it. I can muck around for a number of days and be a lot wiser, googling around or go to a library or such, but I havenīt got a number of days. And Iīve got some educational courses next to my job. I know there are people around here who kno how to create good light rigs and setups to render and such. So Iīm asking for some decent setups from which I can get started.
I know this sounds like a: Give me the files cause I donīt wanna go through the trouble myself!, but most regulars know I ussually try to solve most things Iīm stuck with by myself, so please indulge me.

5+6. I need to render a lot of models for print. idīd be preferred, well one of the highest priority really, that the colors along the renders are uniform. they models seperate need to look the same when printed next to each other.
Also, on screen and printed should look quite similar, colorwise.

I know thereīs people who can help me with this here, not that Iīm not going to look for answers myself now, but I donīt think Iīll find enough in time, so please, if anyone knows something about these issues, DO tell!

thank you.
 
Old 03 March 2007   #2
related to this in a certain way:
How do you merge overlapping curve points (with or without the same handles)?
Suppose I have two circles I break them up to create an s form, how do I make these 2 seperate curves into one single curve while keeping the handles where they join the same?
 
Old 03 March 2007   #3


this is a test with a model I made up quickly. Itīs not the kind of model Iīll need to be doing, but itīs a good example nonetheless.
I need these kind of things to look GOOD. I have made dozens of renders, and these ugly radial black lines are just to sharp. Again, If anyone knows how to soften them, Iīd be happy to find out how.


EDIT: Another thing, the light seems to be cast from the backside! If I place the light in front of it, the back gets lit, if I place it in the back, the front is lit. anyone know why?

Last edited by FreakyDude : 03 March 2007 at 02:03 PM. Reason: curve normals?
 
Old 03 March 2007   #4
I think that you are trying to bite more than you can chew. Your priority should be importing the drawings and modeling, everything else comes second. On technicall related images accuracy is the paramount, everthing else (even good lighting) comes after that.

For importing CAD into Blender, in my experience there are only 3 valid choices: Google Earth KMZ, Wavefront OBJ and DXF. Since you have AutoCAD then DXF becomes your obvious choice. DXF R14 and 2002 seems to work better with Blender.

About importing CAD curves as 3D curves.. sorry pal, this isn't Catia. Blender wasn't designed for CAD 3D drafting, so your next best thing is imporing as mesh and re-tracing by hand with Blender Curves (snapping vertex where it counts).

However, have you really considered the use of having 3D curves in Blender? There are not that usefull for what you want to do. To skin a Nurb in Blender it has to have the same number or segments everywhere, that isn't that common on real world objects.
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Old 03 March 2007   #5
Now that's info I can use! thank you.

A bit of a problem is this:
I'm not so much responsible for making technical drawings, I'm going to be responsible for making pretty pictures out of these technical drawings, in ortographic view mostly.
I can play around with lighting and such, I'll have to tell my boss what we could do best.
They don't like photo's, too much hassle to set up, they want 3d images that look clean and are fast and easy to make.

About these curve thingies, well if obj and dxf give me vertex input only, and I suspect google earth too (don't know about that one yet, will look into it)
how about I import these drawing into illustrator first, then make some kind of path out of it. Blender can chew that right? I like mesh modeling a lot, but a large amount of these drawings can be started by curves and bevelobjects, or combinations of them. the advantage to this (from my point of view, correct me if I'm wrong) is that I can use the original drawings to, after cleaning them up, use as bevel objects and such.
What are your thoughts on this?

I have no acces to any of these dwg files or autocad till sometime next week, so unfortunately I can't really test it. don't have illustrator or photoshop at home either, gonna try finding some free dxf files from the internet and maybe inkscape and files....

Right now I gotta go though. I've got an appointment I can't afford to miss, during the weekend of all times!....


PS. I've checked Catia, Is it something like autodesk inventor? Because that is another application I have to learn how to use.

So in short, I have to make pretty pictures,
best do this in blender/autocad/inventor? I'll check some thingies later tonight, gotta be off now...
Thanks for the info, really appreciate it!
 
Old 03 March 2007   #6
After reading a little, I found that some CAD programs can output SVG files, and those can be imported as curves into Blender. I believe that every single CAD program can import DWG and DXF, so you could try using one another CAD program to convert from DWG into SVG.

About CATIA, I don't use it myself (too much expensive and especialized for what I do), but from what I understand is a continuos curved surface editor and CAM solution. Mostly used in the aerospace and automobile industries, and since recently in the Architecture industry as well.

Doing pretty pictures? Then AutoCAD is NOT your best choice. Blender should fit nicely there.
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Old 03 March 2007   #7
Well thank you again, I tried svg before, but it failed, gave it another go today and I got curves, unfortunately these drawings can be curves, but they weren't clean curves, I did retrace them and it worked, using curves and bevel objects as a base and I have a nice prototype that I suspect will work for my supervisor. So that's a small victory allready.
Made a few dozen renders with different material and light settings. Still not what I aim for, but it is looking better and better as I go.

Will next look into streamlining my workflow, if I have to retrace them anyhow, then maybe importing stuff as meshes instead of curves isn't so bad.

I don't have acces to my imageshack account here, i'll upload images later

EDIT: I did notice the new snapping system doesn't work for curves yet, it's still beta or something i understand, but I don't know if it was known yet.

I haven't showed the images to my supervisor yet, but my coworkers loved them! If this works out as I hope it will, it will not only mean I am a very happy fella, but also that blender is being used in an international professional business!

Last edited by FreakyDude : 03 March 2007 at 01:23 PM.
 
Old 03 March 2007   #8
Okay, I have some new problems regarding this topic. Main one is this:

I can more or less get all files (paths) into blender, be it through svg or dxf, be it by onverting dwg in illustrator or pdf.

Problems are that unfortunately, these drawings don't come out equally scaled. While this is not a blender issue, it's still rather annoying, some of the original drawings aren't snapped properly either, unfortunately. There is no way to unify the scale in blender right? I don't mean clear the scale. With the new snapping framework you can more or less snap meshes, but not (beveled) curves.


The real blender problem I currently have though is this:

I can import, HOORAH!
trouble is, if i import a number of files (import the first, position in scene, save to continue afterwards, start new scene, import, position in scene, save etc) The problem is there seems to be a mix of objects in its "import cache" since on import blender mixes the first imported curve (in a file I allready closed) with the second curve which I imported for the second file.
I can manually clean this up, but this takes forever, I also need to retrace most paths. Easy enough, but timeconsuming. I don't mind the retracing, in fact this allows me to start with clean curves, which hold no flaws, but the fact that my import curves keep piling up with one another is rather annoying. It gets rather hard to find which is which.

I take it that's a bug?
 
Old 03 March 2007   #9
First time I even hear of an import cache, equally about problems with cached imports.

You could restart Blender after each succesfull import. Is a hastle, but should be faster than manually cleaning the files.

BTW, AutoCAD has the nasty habit of saving a cache of loaded drawing blocks on each file it saves, even if the block isn't used anywhere on the drawing. If the problem keeps comming back with you restarting Blender then Autocad is the one to blame. (And unless there is a PURGE command in AutoCAD, the only solution would be to import into another CAD and doing the clean up there before going into Blender).
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Old 03 March 2007   #10
Well I did indeed restart blender after each import, since I kinda figured it was easier and all that too.

New "problem"
Not really much of a problem and I admit I haven't "googled" or Cg searched it yet, but they're closing down here so I'll just post it.

actually never mind, just found it, press esc to CANCEL a render that takes forever LOL.
 
Old 03 March 2007   #11
Running into a new problem: uniform lighting and shading.

I made a few sets of light rigs, information regaring all of them:

http://wiki.blender.org/index.php/Manual/Lighting_Rigs
This was the most usefull one for practical reasons, I could build it according to these settings and tweak away. Unfortunatley even without tweaking it most of the times looks to dark, unless I use ambient color in the world settings tab. But using that makes the image looks blurry.

more info I found:
http://www.blender.org/documentation/htmlI/x5888.html

http://www.itchy-animation.co.uk/light.htm
This one actually does a REAL good job explaining how light is cast, just not how to replicate this within blender.

My first renders accidentically looked good because I used 2 lights which I randomly placed as plain lights, thus casting sharp highlights and shadows on the object.
I'll need some template/default setting for lighting though, so I made a few rigs, following the first link. A number of 1,2,3 and 4 point rigs. When I finally had the sphere evenly lit without hard ugly shadows or sharp overlit area's my metal object looked plain dull and plastic.

Basically I've been messing with lights and shading most of the day and can't get that look I'm after. The material is metal, slighty shiny, but only slightly, the specular isn't that hard, nor that soft. I can make things look metal by tweaking the shading according to:

http://en.wikibooks.org/wiki/Blende...al_Known_to_Man

If I use the settings for metals it initially looks good, however, I need the metal to be more dull. So I play with the spec,hard, ref,rough and raymir settings, A LOT.
Bottom line, if I take away the shinyness, it starts to look like plastic, which isn't what I need.

I've found some info about using fresnels here:
http://wiki.blender.org/index.php/M..._Transparencies

When setting fresnel to the highest value, the result improves, however still to dull.

I've got permission to show some of my test files, they don't contain actual products anyway. just mockups I've made to filter some of the hard cases out. (I so often see that people ask for help but can't show screens and stuff because of NDA, why not create some testfiles that LOOK similar and contain the same problems then?)

The attachment is a T section of a fictional pipe, the problems I have with making this look good apply to the real products too though.
It is placed in a 4lightrig, which comes close to the default rig explained in the first link. It's the most believable image (within my light rig,which needs to be standard and usable for all the final products) I have.

If anyone has some pointers, I'll listen to them.
If people want to see the rig, I can give it.
Attached Images
File Type: jpg Testpipe_dull_metal.jpg (11.3 KB, 57 views)
 
Old 03 March 2007   #12
** Double Post **
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Last edited by Apollux : 03 March 2007 at 12:51 AM.
 
Old 03 March 2007   #13
What you want is called "blury reflexion" and I have two answers for you: Yafray & Indigo.
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Old 03 March 2007   #14
Hey all. New to the board here and relatively new to Blender. I think you may have already tackled the CAD --> Blender issue, but I have been working on a project recently where I had good success with the export/import functions of both AutoCad and Blender. I use AutoCad on a daily basis and there is an export function that will export a model to a .3ds format. The command for this in AutoCad is "3dsout". I was able to import the 3ds file into blender fairly seamlessly using the import feature. The model that is produced isn't the cleanest or smoothest, but it should get you 75% of the way there. You can also set a scale for the model when you import it. If you can get whoever is sending the cad files to you to export the 3ds model, it should make life a little easier for you.

Don't know if this will help, but thought I would throw it out there.
 
Old 03 March 2007   #15
@ron3dfd
Well it was worth the try, since a number of files gone from autocad>illustrator>blender need a significant(not undoable though) amount of cleaning up. And I know blender handles 3ds quite well.
I asked the fellow who provides me with the files, but the command is not recognised. Seached the helpfiles for it and only the "3dsin" command seems to exist.
He noticed that it may be due to the fact that it is Mechanical Desktop's Autocad 2007. and not normal autocad or something, but still, this seems kinda unlikely to me.

I'm currently working on seting up some universal light rig for most of the models.

@Appolux,
Thanks, that's something less abstract to look for, I'll see if they let me install those two.
I'm learning a lot of small things as I mess around with files as I go.
However, there is an image made by bruno akano in the blender gallery with a chevrolet in it, which looks metal and dull at the same time, maybe it's because of the environment, I dunno, but the metal on it, and the wheels, resembles what I am after, it's in the blender internal section. Not to sound a prick, lazy or spoiled, but do I really need to use yafray or indigo to get those kind of results? If it can be done with the internal renderer, would it be such a pain that I better learn to use the other two?
 
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