Discovered this open submission this week. I am going to try and get something (anything) off to them by the end of October.
If i can then i may complete my 2 year MA in 2 months!
But so much to learn – what exactly is a “water-tight” binary STL file…
Due to being so busy with 1) trying to get the sea squirts squirting, and 2) trying to get the Camberwell students all lined up for the MA Forum, i’ve had to do Telesculpture this weekend. 48 hours, from start to finish. Deadline on Monday. This blog is a blow by blow account…
Here’s what i’m trying to 3d-ify:
SAT 9 AM
Stereolithographic file. One of the many 3d file formats. the key thing about this one is that the models are made up of triangles (3 vertices). The format also tells the model renderer which side is the outside. no color, no texture maps, just a list of triangles.
I’m going to use poser to make the figures, for now. Here’s the default figure – he’s called James Casual.
First dump the coloring & shadow – the competition will render the models in a cool white fused deposition modelling cream.
Next try and change something
No idea what the red stuff is but the change worked.
Now i checked to see how to save the object data.
I know i need an STL file eventually – Poser doesn’t do this but it can manage an OBJ file which is a pretty common 3d format by wavefront. So export out as an OBJ file. Now try and find some software which will convert this to STL. After a few efforts found a little program to do this:
3d Object Converter.
Imported the OBJ man and, it works.
It can also export as a STL. When you reimport the STL you can see the difference in the file formats.
The OBJ (left) uses rectangles and the STL(right) uses triangles.
Back to Poser, i want to create an animation. The man walking in a circle. There’s an example in the manual, but it is a mess. Eventually get the man walking in a circle – by deleting the walk i try and manually animate (something like Dustin Hoffman in Midnight Cowboy) and using the pre-defined walk library, but there are several problems – getting the walk path to be a circle was a bitch – the beginning and ending leg positions don’t synchronise – also about 1 seconds worth of redundant frames at the end. Total of 220 good frames though. worst of all is the export AVI crashes the entire machine. but the man walks – starting to think i may get this done in double time. The tidying up of the walk can be left to later.
So i have all these frames as individual OBJ files and i want to be able to take some of them and merge them in some 3d modelling program – and export as a single STL file.
Installed an old version of
3d Studio max (2)
This could import the STL files (converted from the OBJ files) but they look funny, i even managed to link 2 frames together into one – but when the program exports the STL it still looks funny.
what are those holes?
3d Studio max (version 9)
Tried installing a newer version.
tells me i’m missing some dlls, which i download and install.
Still the same problem with the holes.
This must be what they mean by ‘watertight’.
It turns out the holes are a result of a mismatch between meshing thresholds (something like that). there are lots of options when importing a STL file, maybe they could help. or better still this new version can import OBJs. try that.
This has merged two seperate OBJs as a single OBJ. now the OBJ is also made up of triangles so i must have had my previous definition wrong. Still it works – problem what is going on where the two OBJs overlap. are both sets of triangles being rendered even though they may be within the other figure – so redundant in terms of the rapid prototyping – does it even mess it up???
i remember there being something line hidden line removal in 3d to 2d rendering – is there an equivalent hidden triangle removal?
eek – just typed “hidden triangle removal” in google and this page was the third link – going round in circles! hidden surface removal is the proper term. the 3 legs below are zoomed in on (cutting across the model) & revealing the hidden surfaces.
getting nowhere with that – 3ds max seems too complex.
find another 3d package Rhino which does mention watertight STL solids and the avoidance of naked edges. which is not my problem but too many edges?
getting stuck – at least make the OBJ with all the men today – and deal with the hidden surfaces later.
back to Poser. There are 35 ish men in Dores print, lets go for 37 (prime – to tie in with MA Forum video). 220 frames / 37 = every 6 frames.
Just struck me the similarity between the texture used by Dore in his etching(?) and the meshing effect – will make a nice image – using a chest zoomed in on as an exercise yard – i’d be suprised if this hasn’t been done before, but while i’m here…
Took over half an hour to export these 200+ frames. Looked at the Telesculpture size requirements and although they’ll take any file size – they warn over time out for large uploads. Poser doesn’t seem to allow you to change size – something else to sort out later.
This is getting bad, took over 1 hour to load up 36 OBJs into 3ds max, and then 2 minutes to save the file. It’s taking a minute to switch between the browser and photoshop, and a virtual memory warning came up. time to get a bigger computer. this sentence is taking minutes to type, the laptop is crawling through mud – but i have an image.
unfortunately 3D Object Converter couldn’t open the OBJ file (now at 330Mb) or rather i gave up after 10 minutes, so you’ll never know what the 36 man ring looked like as a mesh.
Time for some food, and a defrag…
The aim today is redo everything but at 5% the number of polygons.
Rhinoceros 3d (4.0)
Did some research last night and have moved back to Rhino. It is similar to Studio max but with a cleaner interface and inbuilt help guides. It also has functions to reduce the number of polygons automatically (i’m sure 3ds max has too but the interface is less intuitive). Importantly the test worked. The men OBJ from before had something like 79000 vertices. This can be reduced as low as 5000 and still leave a convincing outline – here’s an example.
Importantly i’ve found a guide to making STLs watertight in Rhino.
On the downside the Demo copy only allows 25 saves so not much room for error.
Rhino dealt with the OBJ->STL transformation and num.vertex reduction smoothly. I really like this program after yesterdays battle. There’s a student priced version at £125 i think i’ll buy. Using freeware 3d Object Converter to check as i go along.
The vertex reduction has resulted in some fraying. Is that the right term?
In a fingertip (red) close up you can see the triangles are still intact – its just that they jag.
The jagging is built into Rhino on vertex reduction – the default option is ‘Jagged & faster’. hmm…
The men on the left are each 3900 polygons = 190KB
Man on right is 78029 polygons = 3.8MB
The entire group of 38 men reduced as above left by 5% = 7.2MB
The only indication as to file size for the Telesculpture uploads is that the upload will time out after a couple of minutes. The objects shown on their poster look smoother than i have reduced the men to. I think it might be best to do the whole thing again at a 50% reduction = 70MB. I’ll send an email off to the organizers asking them for sizing advice. By having larger filesize means less vertex reduction and gets rid of the jagged edge problem.
While i’m waiting for a reply i’ll try and come up with a title of the piece – and a short description. The description will probably be along the lines of “this is my first ever 3d model.”
ARRRGHHH! The jagging has gone but the holes have returned – i must have knocked some parameter off in Rhino.
Looks like i may have to go with what i’ve got.
Redone the whole lot – this time at 50% reduction of vertices. Watertight STL binary file size = 72MB, over 4.4 million vertices.
At least i hope its watertight, and the hidden surfaces will be dealt with by thier prototyping software. i think there’s a chance the hidden surfaces don’t matter, because each STL is hierarchical and each of the 38 figures should certainly be watertight. The jagging has gone and the holes are gone. here’s the final rendered image:
Human Study: Ring
Hopefully the upload goes OK and they accept the piece.
I’ve had enough, i’ll make some reflections on all this next week. Even if the sculpture only comes out 10cm high, i’m technically satisfied – i’ve taken a large first step.