BIM modeling using greasepencil

M by Moult on 19 Mar 2021 # +7 votes

A couple thoughts: I absolutely agree with the spatial approach. It matches a common paradigm of how a lot of architects think. Not all architects, but certainly a lot. This approach and "BIM" is not mutually exclusive. Certainly the existing toolkit of proprietary BIM doesn't follow this approach, but in both the BlenderBIM Add-on and FreeCAD there are no restrictions, so it is good to reimagine our BIM workflows :) Very excited to see how this emerges into workflows that proceed from abstract to concrete, from macro to micro scales, etc.

A thought about greasepencil. I have a few reservations in its use in CAD documentation. Greasepencil is powerful, but I see it as an extension, not a foundation to build upon. The foundation needs to be something agnostic of Blender's Greasepencil, as architects do not work alone, and even use multiple programs. Documentation is an important legal contract where the data needs to be semantic and persistent, and documentation usually combines many 3D models and 2D overlays across many disciplines, especially on large projects. From a purely technical perspective, piping all of this through greasepencil is not very promising. So as long as there is a foundation in place (which quite a number of us are investigating), I would love to incorporate greasepencil as an extension. What this future looks like, I don't know :) Lots of work to do still!

D by duncan on 19 Mar 2021 # +3 votes

( I just enjoy looking at the sketches in this thread )

J by JQL on 19 Mar 2021, edited 19 Mar 2021 # +2 votes

I would say grease pencil is something that would make sense at the start of the project, while iterating for solutions.

After having split a solid into floors and a floor into spaces, geometry foundation is there and different approaches could help consolidate it. Identifying these spaces with topologic and populating them with IFC properties automatically with BlenderBIM's help would be feasible right?

How soon could that help us integrate BIM in a project? I think that holds potential.

After this was done, we could start using other tools that could create constraints on geometry, generate 2D symbology like structural axis or section lines and floor heights...

Then we could move on to higher details. At that point grease pencil could loose it's value as we might need very accurate tools, but I have some ideas on how it could further be used to populate openings, create complex structure concepts and models for hvac and plumbing and even electrical schematics.

Blender has many ways of modeling stuff and that can help it happen. On higher LOD blender's direct modeling tools will be needed but it's a continuous environment for doing everything.

I hope we can find a way to bind the required direct modeling to the initial geometry from grease pencil, topologic and constraints, so we could have some kind of non destructive modelling workflow.

That workflow would be the mantra for connecting concept to construction documentation and if that is possible grease pencil will always be useful as it is the base that can be refined without loosing it's raw potential.

We could think on increasing LOD as a stack of Blender modifiers. That stack would affect the base geometry created with grease pencil. Redraw the base, identify the cell complex, find the floors, spaces, staircases and elevators, and reapply the modifier stack on the new geometry.

Isn't that what Topologic is proposing and Topologise is trying to achieve?

Isn't that what geometric nodes and Sverchok allow?

And archipack can't it be integrated into Sverchok for this higher LOD?

As well as other projects around here?

Isn't all that bindable to BlenderBIM in order to create a structured IFC, extract 2D documentation and schedules?

And if we work with a Blender modifier stack for higher LOD can't we have simultaneously a model for documentation and presentation and a model for analysis?

If we find a way to bridge all of this wouldn't we be able to really change how we design. How great could that be for the whole world if that would be done in an open source environment...

We have all the tools to start with. I would love to discuss how to bind them.

M by Moult on 20 Mar 2021 # +2 votes

Just for those reading through this thread who might've forgotten this thread, thought I'd bring it up :) Here is a fun example of mixing conceptual geometry with BIM: https://community.osarch.org/discussion/comment/1669

J by JQL on 20 Mar 2021, edited 20 Mar 2021 #

@Moult Do you know how the original model was created using grease pencil or was it modeled and then drawned upon it with grease pencil. I'm trying to understand how it works.

@JanF I've downloaded Blend file too and I see that once I draw an enclosed shape it auto extrudes the set plan height, if I keep drawing it splits it.

I think making a coesive toolset for this would be a matter of creating a series of Sverchok scripts to make things like boolean operations, bevels, splits, etc, and put them all in a toolbar.

Am I right?

Is this what you mean with:

@JanF said:

My current concept is actually to create a set of "modules" (if you are familiar with Darktable that kind of modules I mean) - each module acts independently and can be turned on or off (sort of like adjustment layers in Photoshop, now that I'm thinking about it), it doesn't change the original geometry, but takes it as a source and creates a modified copy, this way the whole thing stays completely parametric, the only data in the file is the original geometry, the modules used and their parameters.

Modules:

GP to lines - takes GP strokes and turns them into straight lines

Cleanup - takes straight lines and searches for lines with similar direction and colliding ends to turn them into a single line

Axes recognition - takes straight lines and turns them into straight lines with an appropriate axis as a parameter

Axes snapping - takes straight lines with axis parameter and turns them into lines parallel to one of the axes

Connections recognition - takes lines and turns them into lines with lines they are connected to as parameters

Trimming - takes lines and trims the ends that go over connected lines

Dimensioning - takes lines and moves them according to the dimension input

Connection keeper - takes lines with connected lines as parameters and extends/shortens them to keep the connections

adding openings - takes two sets of lines and creates objects on their intersections

As of now I covered all but 2, 7 and 8 in my demos, points 2 and 8 should be easy, 7 should be in principle also easy, but I have no idea how to make an UI for it.

J by JQL on 20 Mar 2021 # +4 votes

Just tried it today and I'm officially in love with Grease Pencil...

I still don't dominate navigation as I miss touch input, but the pen glides on shapes like it's 3D paper.

J by JQL on 21 Mar 2021, edited 21 Mar 2021 # +3 votes

I'm still too afraid to commit myself to start modeling in Blender, however I tried using these GP sketches further.

There are some issues that I came across:

GP are very innacurate in nature. That's why I like them for their original purpose, but that's probably the question that @JanF is trying to address on his experiments in order to achieve accurate modelling. If you want, I would love to share some ideas on how to address those questions in an intuitive way, as I've been trying to think about that in a user perspective. I can learn Sverchok as I go along.
I know GPs can be further edited or converted to curves or meshes, but at this point, for now, it's easier to use them as reference and create geometry with other modeling tools.
As modeling in Blender still isn't for me, I tried projecting these grease pencil strokes into a texture UV unwrapped into the model so I could export it and model it in my modeling app. This is not possible. GP's can't be baked into model's textures.
So I started using Texture Paint to texture. This works as it results in the texture being exportable along with the model.

Texture painting isn't as fluid as GP though. You can only paint into one object at the time and changing objects requires changing to object mode, selecting the next object and then go back to texture painting mode. We loose a lot of fluidity in the process and the experience is not as dynamic as applying grease pencil strokes on top of models.
Texture painting turns out to be something usable for me now as I can deal with it as something embeded in the actual model. It's like 3D paper. Sketching and iterating ideas at a conceptual stage could become very rewarding if minor workflow details would be improved in Blender. The idea that for a single model we can save several alternative textures and compare them just by changing them is very interesting for collaborating and discussing solutions.
As I have other tools for painting, I tested this on Substance Painter. SP allows painting through multiple objects and materials, or using materials with UV tiles. I could then paint on the building and the ground. In other scenarios I'd be able to paint on buildings composed of multiple objects easily. Here's a doodle I did: (I had some face normal issues that I didn't fix, so I don't show the ground here)

I exported the textures created in SP and imported them into Sketchup (my main modeling app). I then modeled based on what I textured, rendered it inside Sketchup with a Sketchy edge style (first time I used that in my life) and the final result is this:

I can see myself creating some presentations with this method already, so thank you for this discussion.

I think a similar method could be achieved exclusively with Blender if:

Grease Pencil's could be projected/baked into textures of a model. That would be perfect;
It would also be very interesting to have Blender's texture painting being able to work across multiple objects.

Using Grease Pencil with Sverchok for actually editing geometry is still a very interesting and valid idea and I will keep exploring how to use Grease Pencil Strokes to affect geometry, how they can be converted into accurate geometry on the fly or in a post process, with more control from the user and by imposing some geometric constraints to a geometry that was first created without that in mind.

It's also interesting to think when, in a practical workflow that should happen and how or for what purposes.

I'd love to discuss this further.

D by DADA_universe on 22 Mar 2021 # +2 votes

@Moult said:

A couple thoughts: I absolutely agree with the spatial approach. It matches a common paradigm of how a lot of architects think. Not all architects, but certainly a lot. This approach and "BIM" is not mutually exclusive. Certainly the existing toolkit of proprietary BIM doesn't follow this approach, but in both the BlenderBIM Add-on and FreeCAD there are no restrictions, so it is good to reimagine our BIM workflows :) Very excited to see how this emerges into workflows that proceed from abstract to concrete, from macro to micro scales, etc.

A thought about greasepencil. I have a few reservations in its use in CAD documentation. Greasepencil is powerful, but I see it as an extension, not a foundation to build upon. The foundation needs to be something agnostic of Blender's Greasepencil, as architects do not work alone, and even use multiple programs. Documentation is an important legal contract where the data needs to be semantic and persistent, and documentation usually combines many 3D models and 2D overlays across many disciplines, especially on large projects. From a purely technical perspective, piping all of this through greasepencil is not very promising. So as long as there is a foundation in place (which quite a number of us are investigating), I would love to incorporate greasepencil as an extension. What this future looks like, I don't know :) Lots of work to do still!

I think we need both approaches, being not mutually exclusive - barring developer / time constraints (which admittedly are considerable), as they say, you can ride a bicycle while chewing gum. While appreciating quite well the need to prioritize round tripping / interoperability we should also not lose sight of opportunities native to Blender that might not be immediately replicable or even applicable in other tools. Besides, if a feature or workflow that's unique to Blender becomes quite successful, and popular, it most likely will get copied in other tools, meaning these efforts don't have to solve all the problems for all the tools, but can inspire new and hopefully more nuanced approaches across board, without prejudice to the long game of interoperability. But yes, it's clearly a lot of work.

D by DADA_universe on 23 Mar 2021 # +2 votes

@JQL, apparently you can sketch on a proxy object like you've done and get a mesh out of it, in Blender, without having to project or bake textures. Editing the mesh is straight forward from that point, with basic knowledge of mesh handling and polygonal modelling in Blender, making it unnecessary to export out of Blender to get a final result. You can sketch on the proxy, make a mesh out of the sketch, edit the mesh, and sketch on it again:

J by JQL on 23 Mar 2021 # +1 votes

I new that Grease Pencil could be converted to meshes (and the other way around). I was afraid of that as it meant learning a lot, but I will follow your lead. It might get interesting indeed.

Thanks!

J by JQL on 24 Mar 2021 # +1 votes

I've tried it and it does hold potential. A lot. I just feel modelling in blender is not easy or nice. Too much eye balling and very hard to constrain geometry to the accuracy I want.

I'll keep pushing, slowly, possibilities are great.

D by DADA_universe on 31 Aug 2021, edited 31 Aug 2021 # +5 votes

I've done some design sketches with Grease Pencil recently and it is indeed super intuitive. I could sketch over an underlay (so you can bring in initial scanned paper sketches or images), work in layers (separate ones for doors, windows, walls), have a separate Grease Pencil Object for each floor, and then I could do 2D in 3D by translating the first floor above the ground floor by the required head room and sketch in the connecting stairs. Using a digital pen, it didn't feel like 'modelling' or 'drafting' at all, it felt more like sketching.

I sketched in a facade in Grease Pencil, made it into a mesh, extruded and shaped it in edit mode to give it volume, and went back to sketching on it in Grease Pencil. It was cool being able to export each GP object out as SVG directly and the SVG played fine in Inkscape. One thing I wished for while using this workflow though, was to have maybe custom GP brushes for walls (that automatically give you double lines spaced out by a width you can enter), and doors and windows (of sizes you can set), already you can set line weights and layers, and you can constrain your line to run parallel to any of the axes or a radial constraint. Those custom brushes will in my estimation make the GP work flow even more applicable to a sketchy CAD workflow, and a tighter integration with MeasureIt_Arch would mean you can complete your entire sketch design proposal with GP, including indicative dimensions and annotations, all of which you can export straight to SVG (and as PDF).

I like the demo utility @JanF has developed using GP and SV nodes, and the strokes based workflow it supports, it would be cool to have this workflow based on brushes which I have described as an alternative in the same suite of tools.

*Edit, not sure if brushes best define the intended approach, but I checked and there exists a multiple strokes modifier which acts on grease pencil stroke to give parallel lines as described, with adjustable settings to boot (see screen shot below). Perhaps the way to fuse this with JanF's workflow would be to draw with the modifier activated but have it such that when you place the cross strokes for creating doors and windows, as the components are created in 3d, 2d symbols are also dropped in place, and you can toggle off the 3d mode to focus on 2d sketching if require. Reminder here that the aim is to achieve really cool early stage concept drawings, however I see potential nonetheless, with further optimization, for even full blown CAD documentation. All in all still pretty keen and enthusiastic about getting more out of Grease Pencil.

A by Ace on 1 Nov 2022 #

Hey @Moult

I haven't used it in awhile but I just noticed the Wall from annotation tool is no longer there?

Is it still possible to draw walls and instance from a line like in this video: