Brick catenary arches

[Anonymous]

Hi,

i've been reacquainting myself with Archicad after a few years of using other programs. After hearing about it's new shell and morph commands, i decided to give it another go. I'm currently doing my final year project where my structure basically consists of a series of large catenary arches, not too dissimilar from a brick viaduct. I would have normally modelled something like this on rhino/sketchup and the drafting in autocad but since time is tight, I thought I could kill two birds with one stone by using virtual building program such as Archicad. I was no expert using AC before so yet again I feel like a bit of a novice!

I have tried 2 different approaches to drawing the arches. The first was using the shell command and extruding a spline profile to form the arch, then lifting it upright and moving it into a straight brick wall of the same thickness. I then used the Trim Elements to Shell command to form the arch opening in the wall. http://postimg.org/image/tbbmjb8uf/
This seems relatively straightforward but my main problems is trying to align a brick texture to follow the line of the arch. I would maybe like to use the sketch renderer but cant get the proper textures on the arch.

The second approach was using the morph command. Again, I drew a spline, offset it, closed the profile and extruded it to form the arch morph object. I saved the morph in the library as a door but when applying it to a wall, the opening is the rectangular extent around the object and not the arch. Frustrating! The photo shows what i mean:

The morph allowed me to draw panels along the face of the arch, where I could apply textures individually and align them along the curve of the arch to some degree of accuracy. However, when trying a quick render, the textures were back at their default position as shown in the photos.

Sorry for the long message, I hope its clear what I am trying to achieve! Can anyone shed any light on this or maybe suggest a better way of drawing the arches? I also have Artlantis, is that a better way to apply textures? Any help would me much appreciated, I feel like i have wasted a lot time trying to get this and deadlines are fast approaching!
http://postimg.org/image/d61sa05mb/
http://postimg.org/image/vrkkl5a0h/

[Anonymous]

Thanks Dwight,

it took me a while to model the arch as you described but it looks well. The only problem now is a noticeable drain on my memory and processor when placing them due to their size and complexity. Considering i'm using dozens of these in my building i might be selective and only use them in my renders and use the plain flat edged arches everywhere else.

Hmooslechner wrote:
The matehmatics of an catenary (Kettenlinie?) is still too complicated for me ( i thoght about ropes - thats mathematicly just the other way round).

If it would be possible for me to calculate exact differences on a hyperbolic curve this would be nearest to it i think. But that takes till july and august, when i will have more Time.. Its just a hobby now..

No problem Heino, i wasn't expecting you to draw up a catenary straightaway! thanks

[Dwight]

You've modeled the individual brick units, now go back and model the grout as a simple, single block. Put the brick arches in a special layer toggled as needed, swapping the basic form defined by the grout blob for routine views.

You can also render the flat face of the arch and use that as your hi-res texture map. Use the 3D Align tool to make it fit.

As to math, the catenary is defined by: y = (cosh(1) - 1) x 2 + 1 so Mooseman should have no problem fitting that into a twelve line GDL script. [joke].

[Anonymous]

Dwight wrote:

You can also render the flat face of the arch and use that as your hi-res texture map. Use the 3D Align tool to make it fit.

This seems like a good solution as it wouldn't drain my resources. I've rendered the face of the arch. How do i apply the custom texture to the arch? I've looked around a bit but can't find a solution. Do I customise the GDL scripting? (I wouldn't be too comfortable doing that!)

[Dwight]

Use the image as a material texture. Apply the material. Align it using the 3D Align tool. Viola!

[Anonymous]

I've applied the material but for some reason can't align the texture.

Am I right in selecting the element then Design>Align 3D Texture>Set Direction? When I do this, it asks me to click on the main surface of the selected element, which I do and then nothing happens.

Sorry if i missed something really obvious!

[Dwight]

So you aren't left hanging on Sunday night, I'll investigate and post a reply soonest. You'l be helping me defer some difficult design decisions on another project so that I'll run out of time to dither around trying to make a better solution.

[Anonymous]

No worries Dwight, take your time! I can work away for the time being on the rest of the project, this is only for when I come to rendering it at some stage.

I appreciate your help!

[Dwight]

I've duplicated the condition and find no problem mapping or aligning to the side of a complex profile arch. So i think your mousecraft needs work. You've got to hit a place on the material surface - a node is best - to change the alignment. Also know your exact size since the mapping assumes 1.000.

Another way to do this is to make your object surface start at the origin - where all object mapping also originates.

[David Maudlin]

trunmaster wrote:
Am I right in selecting the element then Design>Align 3D Texture>Set Direction? When I do this, it asks me to click on the main surface of the selected element, which I do and then nothing happens.

I think you want to Set Origin, not Set Direction.

David

[Anonymous]

I have set the origin already. I think I have it now, I just cropped the rendered image of the arch to make sure the origin would begin right at the base of the arch. The new arch texture does not appear in the sketch renderer but I can render the previous custom arch with the individual bricks for that if I need.

Thank you all for your help!