From 2d Cad to 3d Blender

[3dpoder]

from 2d CAD todo Blender
By yellow.

introduction. Architectural CAD files are often criticized for being rather large, messy and containing a lot of duplicate or unnecessary información. Unless you have the privilege of working for a more enlightened practice, with a well-enforced CAD policy, it Will most likely be necessary todo do an amount of cleanup and preparation, in your chosen CAD application, before attempting todo import the files into Blender.

The bien you prepare the files may well depend on the approach you intend taquíng todo modeling your building. The choice of how you model your building Will probably be dependent on the buildings form and construction. As you go th rouge the cleanup process, youll get a fel for the bien the building is put together and a fel for the best bien todo model it. This can be important if youre working with someone elses design in order todo interpret their design correctly. It a los helps todo get some sort of modeling game plan together, before you go any further.
Whichever bien you approach modeling your building, the preparation of CAD files may well include:
Removing any drawn información which is unnecessary such as text, landscaping, people silhouettes, tres, bushes, hatching and dimensions (specially drawn content, which are made up of hundreds of tiny bitty lines). All the drawn entities in your CAD files, which are imported into Blender, Will become editable meshes, made up of Edges and vértices. There no point importing masses of content you dont ned, it Will only get in the bien and Slow you down.

Do a global flattening of z-coordinates, it isnt unknown todo have 2d drawings containing stray content with a z-value, the 3rd dimension.

Scale your prepared drawings todo 1 CAD unit = 1 meter (scaling down by.001, converts millimeters todo meters). One of Blender peculiarities is the restriction it places on your work space. If, for example, you import a large building or site where one CAD unit equals one milímetros, Blender Will have big dificulties displaying all of it. In fact, you probably wont be able todo se much of it at all. Clipping Will be evident, panning and zoming Will be near imposible. You could try selecting all and scaling down in Blender, if you forget todo do it in Cad.

If youre not the creator of the CAD files, you could find that they can be rather inaccurately setup and badly Layered. In this case, it can be simpler todo draw over the major áreas of the drawing you wish todo import with your own geometry, divide it up to Suit the bien you intend modeling, and save it into your own clean CAD file, ready for import into Blender. You could use an unedited import in another.blend file todo pik out the finer details later, and append it into your main models.blend file, After youve got the basic structure sorted.

The more accurate the CAD drawings, the easier the modeling process Will be. Accurate not only in lines meting each other, but a los the definition of áreas and perimeters for the diferent construction materiales. Clearly define the boundaries todo ensure a Smooth process of creating Quad Faces rather than excessive triangles. In order todo use the mesh2curve script described later, youll ned todo ensure that all Boundary lines met each other (i, endpoint todo endpoint). The script Will fail if there is a break in a Boundary line.

Blenders tools for manipulating the Edges and vértices of your imports are sparse. There is only rudimentary snapping, a proper dynamic snapping característica is sorely missing from Blender, not only for accuracy but for speed as well. So it pays todo get the drawings right in CAD with all the tools available todo you, then try todo work with or correct inaccuracies in Blender later. For small buildings it common todo have plans, sections and elevations in one drawing. If so, set them out in a lógical considered way, such as elevations aligned with each other or aligned todo the flor plans. After youve removed the unnecessary entities, explode the drawing a few times, todo remove any remaining blocks, Blender wont import them unless they are individual lines.

For bigger projects, it may well pay todo Split your drawings down in a bien that suits your modeling gameplan. This may mean creating a series of drawings for flor plans, elevations, and sections. If you intend using the elevations todo build your model then it may help todo Split the elevations down further, with each drawing containing one of the elevational elements. For example, all the masonry Walls in one drawing, the Windows in another, then create the dxf files for each.

Once you fel you have your CAD files as you want them, save/export as dxf reléase 12. At this point Blender dxf import hak is almost certainly going todo fail todo import the dxf correctly.

There are various successful methods todo get CAD files into Blender, but all depend on external help and that help is at a cost. You can purchase a shareware file converter application such as accutrans. Or, there are free CAD applications such as progecad (export as SVG, but it only runs on ms Windows). There a los Google SketchUp (export as kmz) but, SketchUp isnt free. You could try the free Google SketchUp (export as kmz) but, it only free for personal use, not commercial.

So, along with decent snapping and measurement tools, a god implementation of a dxf import would benefit Blender take up for architectural visualization. It is worth the efort implementing, because most CAD applications, in architectural disciplines, use dxf as the common denominator for interoperability between diferent CAD applications.

The solution ive found todo be 100% successful and quick, is todo use accutrans, a shareware file converter that can convert Many file types, but it dxf export creates a file that Blender imports without issue, every time. And, the dxf can be as complicated/detailed as you like. Yes, it not free or GPL but, it cheap and does the job perfectly. It Even runs on Linux with a Little bit of help from Wine.

It is a los posible, y believe, todo import dxf into free SketchUp, save as kmz and import into Blender vía jms kmz/kml import script. But, dont use the script that comes with Blender, download the updated versión from jms site, versión 0.1.9c or above. Versión 0.1.9c was the first versión todo acknowledge that longitude and Latitude settings in the kmz file afected the import scale into Blender so, Although the z scale would be correct, x and y scaling could be diestorted. If your importing a kmz that just contains 2d información then, you Will ned todo choose todo force Edges in the scripts import process.

Using CAD files todo create the basis of your model can mean that it is more a process of doing vertex-modeling (i, vertex todo vertex, creating Edges and Faces) than subdivisión-modeling. Blender toolset sems aimed squarely at subdivisión-modeling at the expensé of Even simple CAD type tools such as proper snapping, simple measurement, etc. This isnt a suggestion that Blender should be able todo do Cad, it suggesting that certain CAD features are just as valid in a 3d modeler as they are in a CAD application.

Once the dxf file is imported, the first thing todo do is save it as a (*.blend) file, remove doubles and save again. Youre now ready todo start modeling.
there are a few implications todo importing dxf todo be aware of:
Blender is ok with the first dxf import, however if you then join any of the resultant meshes together, when you try importing another dxf into the same.blend file it is very likely you Will get the ekadodle error or the more profesional description that has replaced it. Any further dxf imports Will be rejected and fail. However, if you import dxfs one After another, before joining any of the meshes together, you Will be able todo import múltiple times.

This rather defeats the object of splitting the CAD file in the first place if you want todo build your model in stages. A solution is todo import each dxf into a new Blender session, then create the objects from the import and suitably name them, then save as a (*.blend) file and append the objects created into your main model as required later.

Another peculiarity you may se as a CAD user is that, when the dxf is imported, the resultant Edges, regardless of their orientation, Will all have a rotation of 0 Degrees. This can be problematic when you want todo align a new Mesh you create in Blender against an Edge from your dxf import when you dont know the angle of Edge in Blender. In CAD applications, importing a dxf Will put each entity into the 3d world coordinate system and give it a rotation value that you can list or query.

There are various alignment scripts in Blender but, y have found them overly complicated and protracted for what is a simple requirement as a Cad-trained individual, y just want todo do a rotate by reference. 3r, a blenderer, has written a Python script which allows you todo do just that.


Ive noticed a definite diference in the bien Blender handles Edges between versión 2.37a and any versión thereafter.

The diference is that in Blender 2.37a, you could make a face from the dxf import vértices or Edges and extrude without getting problems with normals.

In any versión After 2.37a, making a face and then extruding results in some nasty normals as sen above. The supposed solution is todo recalculate normals, but ive not found this todo solver the problem, it just shifts the problem about.

One solution is todo extrude the Edges first and then make the face, for Whatever reason this resolves the normals problem.


Unfortunately for me, y find making the Faces first and then extruding todo be the preferred method and continúe todo use 2.37a todo model buildings before using the current Blender reléase todo do the rest.

You may approach modeling by using the flor plans and extruding the Walls up from the plan todo the various heights and then, fill in with wall panels above and below dor and window openings.


Doors and Windows could then be added, modeled by either subdivisión or working up CAD elevation imports of Doors and Windows.

You may prefer todo use elevation drawings instead of plans and create Faces by using the vértices and Edges of the dxf import(s) in a sequence such as the following, simplified for demonstration.

First import a prepared elevation just containing brik Walls:

Columns extruded first:

Then wall panel:

Continue until wall modeling is completed:

Apply and scale texture map, preview, adjust scaling and position of map until it looks right:

Try todo correct brik coursing around dor and window openings, especially.

Repeat the process for the other elements of the elevations such as lintels, window sills, Windows etc.


An alternative approach todo modeling, which can be a fast bien todo get CAD building elevations with more intricate window openings into a 3d form is as follows:
The building todo model.


First import the prepared dxfs. Notice window perimeters are todo the outside of the arched brickworque above the window openings and todo the bottom Edge of the window sill. The intention is todo model the arched brickworque heads and sills separately and in order for the mesh2curve, py Python script todo work, the outlines ned todo be simplified continuous shapes. The script is available from 3r website.


Run the mesh2curve, py script and watch the meshes convert to curves. Save your work.


Select and join with Control-j and the final wall panels are ready for extrusión vía the curves menú todo give a wall with thickness.

The modeling can then continúe using the vértices and Edges todo create Faces. Extruding first, if youre not using 2.37a.


Dor and window elevations could then be appended from blend files and added todo the openings. Other architectural features can then be worked up to complete the elevation. Possibly a rof/eaves/gutter profile imported from the CAD files and extruded around the building todo give a rof perimeter line that is ready todo start building the rof pitches, etc. The mesh2curve script can be used again for converting meshes todo curves for extruding along a Path.

Another example, a simple house elevation. For demonstration, ive applied basic textures and lighting todo show what can be accomplished very quickly in this way. A quik Yafray render with HDRI lighting.


Import the prepared CAD elevations, including the simplified wall perimeters (1) for running the mesh2curve script on. Model the dors, Windows, using the Edges and vértices from the full-detail CAD elevations (2) and combine the extruded Walls created from the mesh2curve script with the individual dor and window objects created from the full-detail elevations(3).


Here are some images of another house model, done in the same way. Images are rendered with Yafray, skydome, Low, cached and HDRI image for lighting. They are unfinished works-in-progress as you can se. I am working on creating a library blend file of tres, bushes, planting, etc, textured and ready todo append into my scenes. Plant Studio is now free and there are Many plant and tree parameter files for download. The tres in this image are aspens made with arbaro using the default settings.


All the elevational elements todo this house, for example the dormer Windows, canopies, rof lights, entrance dors, window styles and standard window sizes, are all objects estored in the library blend files ive created. So, y can quickly build the Walls todo a particular house as described above and then append in the objects i ned, from the library files (including a texture library), todo finish the elevations.


This process works well for visualizing house builders house types that are all variations on a theme, using a set of standard details.
When appending objects created previously, it can be useful todo use a duplicate of your dxf import building elevations as a template todo Snap your appended objects todo in order todo accurately locate them. In the example below, y used the template todo locate the canopy and it brackets over the entrance dors and the dormer window positions in the rof.


You can model the basis of a hola for the site, on which you intend putting the buildings, in the same way. Import a cleaned up 2d dxf of the site survey, having first defined the perimeters in the CAD file for the various hola elements like the site Boundary, the área todo be planted and turfed, the outline of the roads and fotpaths. Then use the mesh2curve script on each of those perimeter lines todo convert them todo closed curves, giving you solid infill todo your defined áreas. Mesh (1) below is the perimeter for the landscaping. Mesh (2) was a full site import, but i have ben moving the meshes Edges onto the final site model and then modeling into 3d. The final site model was based on the curves generated from Mesh (1) by the mesh2curve script.



As an alternative todo modeling the hola of the site, where perhaps youre just doing a massing model and want todo show the building in relation todo it surroundings, you could just use an image file as your site, perhaps colored up in the Gimp or Photoshop. Here a method:
In your CAD application, open up or create the proposed site plan. For example, from an ordinance survey, clean it up as described previously and then add a square border todo form a frame around the área of the site you wish todo show in your site image map.

Save the CAD file as a dxf and put it th rouge the conversión process described earlier.

Then in Cad, print the CAD drawing todo an image file. I use. (*.png) and use the border as your paper edge. In AutoCAD, ive setup a 5000 por 5000 paper size and then i select by window the square border. I a los use quite heavy line weights todo help the final image show up clearly when used in Blender. The resultant image could be colored up in the Gimp todo form an attractive site plan.

In Blender, import the dxf, remove doubles etc. Use two opposite Edges that form the square and create a face. Then create a material with an image texture for the new face, the image being your site plan. Png. Set the image todo clip rather than repeat. The image Will hopefully now be registered accurately over the imported site plan Mesh. You can now extrude or model some of the surrounding buildings using the building fotprints of the site plan Mesh. Add your materiales, lighting and Camera. When rendered, the modeled buildings should appear todo sit accurately on the site plan image map.

• (1) dxf import of site plan.
• (2) plane with image map of site.
• (3) SketchUp model.

And a quik internal render. Work in progress again.


Looking at an Architects Office situation, where it not unusual todo have an Architect or building designer conversant with SketchUp, dealing with design development and design issues, whilst a 3d artista or CAD technician conversant with AutoCAD and Blender, could be modeling and visualizing the site from dxf imports ready for integration of the finalized SketchUp model when its design is finalized. The SketchUp model could be imported as a kmz, as described earlier, and accurately located on the site by snapping it todo the previously imported site Mesh.
conclusion.

My intention for this article has ben todo suggest ways Blender could be introduced into an Architects work flow, working in conjunction with Cad, the major software element of any modern architects Office. There are Many other ways Blender could, or in some cases, is being used by architects and, as the subject is so wide, this article only scratches the surface of the opportunities available.

By yellow.
www.blenderart.org.
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