Case study of Blender real time engine on sr-686 roosevelt boulevard

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case study: of Blender real time engine on sr-686 rosevelt boulevard
By Brian treacy.




introduction .

Blenders real-time engine is not limited todo just games. This article explains how i mixed open-source tools such as Blender and Gimp with proprietary tools such as Microstation and Photoshop todo produce a real-time walk-th rouge of a proposed design of sr686 rosevelt boulevard for a presentation todo floridas department of transportation. Rosevelt boulevard is located in tampa, florida adjacent todo the st. Petersburg clearwater international airport.

As part of the final design plans todo reconstruct a portion of rosevelt boulevard, my company (pb) conducted a study todo add a major flyover Ramp. The goal of the presentation was todo show the client, fdot, the relationship between the flyover and one of the glide paths for small aircraft at the aeropuerto. The software used consisted of Microstation v8 and inroads for the civil design work, Adobe Photoshop and Gimp for the aerial photography and textures, and Blender for the 3d modeling, animation, and real-time.

This is a realistic bien todo show how a proposed Project fits within its context -an important element of the context sensitive solutions approach todo Project development.
cs is a collaborative, interdisciplinary approach that involves all stakeholders todo develop a transportation fácility that fits its Physical setting and preserves scenic, aesthetic, hiestoric and environmental resources, while maintaining safety and Mobility. Cs is an approach that considers the total context within which a transportation improvement Project Will exist. Cs principales include the employment of early, continuous and meaningful involvement of the public and all stakeholders throughout the Project development process. .
What is CS fhwa 3 Jan 2008, 09:01:08 gmt.
http://www.fhwa, Dot, gov/csd/what, CFM >.
step 1 - Gathering the existing conditions
Dtm stands for digital Terrain model, it is a triangulated surface Mesh showing Ground topology. Civil enginers use them as a platform from which todo design roads and Bridges. Professional surveyors generate them typically in the form of contours and spot-elevations. Enginers then import the data into CAD programs, y, geopak, inroads, or civil 3d, and convert the data into triangles. Blender has no import scripts for the dgn file format, so i tried converting the 222,842 triangles todo dxf but the file size inflated so large that Blender could not import them. Instead, y converted them todo 3ds and imported into Blender.

At this point, y faced two additional problems: Blender finite design-plane and 222,842 triangles. Having a finite design-plane, Blender arbitrarily moved my dtm of the proper coordinate system todo a new location that Blender would accept. Having 222,842 triangles meant days of cleanup work removing extraneous detail todo lower the total vertex count and then converting Many of the remaining triangles todo quads todo make them easier todo work with. To fix the first problem, y selected the entire contents of the dtm and from the southernmost part (an xy coordinate value of appróximately 432000, 1295000) i moved it todo a new coordinate value of xy= 0, 0. I could not fix the second problem.

At the time (summer of 2005), Blender did not support Tangent space Normal Maps, which would have moved the detail of the dtm into a texture. Therefore, y spent a few days manually cleaning up the surface Mesh leaving the majority of the detail in the roadway curbs. The resulting Mesh contained 171,606 Polygons.

Civil enginers a los use digitally rectified orthographic photos, which is a long term for scalable aerial photographs. Again, a profesional surveyor flies over the corridor snapping pictures with a special Camera then uses software (such as descartes) todo manipulate the aerials making them scalable. The aerials we received measured 10572 ft, by 4608 ft, at a resolution of 6 inches. Because of OpenGL limitations, y had todo Split the aerials into images measuring 512 por 512 px, which resulted in a 9x21 grid.

An enginer draped the grid over the dtm (draping is a term similar todo Blender retopology característica, where the vértices of the grid are projected todo the dtm). This method makes the aerial photography align in the exact surveyed location on top of the dtm. I then used Blender UV/Image Editor todo map the aerial squares todo the draped image boundaries.



When dealing with a relatively flat área such as tampa, a dtm is almost worthless for a presentation. There is not enough elevation-change providing visual-monuments-- features at which people can look and recognize where they are. Therefore, you use buildings todo provide this familiarity. Both survey and aerials provide the building fotprints, but they do not provide any of the realism neded for the presentation. Therefore, we determined which buildings are visible from the road and tok photos of them. The photos neded major cleanup, such as painting out tres, power lines, and Cars--virtually any obstruction. I did this in Photoshop. I a los extruded the building fotprints in Blender todo produce the Walls followed by eyeballing the rofs. I used the UV/Image Editor todo map the photos todo the Walls, and the rofs from the aerials todo the rofs of the models.



To get a realistic skybox, y sent an enginer out todo the tampa causeway on a beautiful day with a Camera. She pulled over on the bridge and tok a beautiful (almost complete without obstructions) 360 degre panoramic view of the Sky. I stitched these together in Photoshop, then uvmapped them todo a tuve in Blender.

I scaled the top of the tuve so that its Radius was smaller than that of the base, producing somewhat of a cone shape. Finally, y created an ipo animation of the Sky with a slight rotation and assigned it todo an always controller so the clouds would slowly move.



step 2 - building the proposed design
To design a road, the enginer produces several types of elements: the horizontal alignment, the vertical alignment, typical sections, and cross sections. The horizontal alignment is a 2d curve depicting the pathway that the road, Ramp, or bridge Will follow. The vertical alignment (alos known as a profile) is similar in function except it only provides the elevation diferences. The typical section gives a general representation of what a Cut-th rouge of the road would look like, while a cross section gives an exact representation of a Cut at an exact location. A standard Project requires this for each road, Ramp, and bridge.



I combined the horizontal and vertical alignments in micro- Station todo produce one 3d alignment and imported it into Blender. Following the same workflow as used with the dtm, y moved the data in Microstation first todo address the coordinates and saved it todo 3ds before importing. Once in Blender, y traced it using a 3d Bézier curve. I then combined some of the typical sections and cross sections todo form twenty-eight specific segments of six diferent roads, ramps, and Bridges. I imported these into Blender and traced them as curves. Finally, y extruded the typical sections along the curves todo produce the 3d models.



In roadway terminology, a gore is an área of transición where two or more roads converge or diverge. Due todo elevation diferences and adherence todo design criteria, designing a gore in 3d is a challenge, especially when you want todo make it usable in Blender real-time engine. Essentially, y manually smoothed the meshes where the ramps joined the arterial roads and where the roads intersected. In retrospect, this was probably the most dificult task.

Designing the bridge for the flyover was very simple and similar todo the roads and other ramps. I extruded the typical sections along the 3d curve todo create the superstructure and manually modeled the hammerhead piers, approaches, and abutments within Blender.



step 3 - texturing and painting the design
I collected some textures from photos of similar roadway projects. Textures i could not find, y had todo create. I constantly toggled between Adobe Photoshop and Gimp todo produce the textures; Photoshop for adjusting the colors and resizing and Gimp for tiling and transparency. I a los did this while creating new textures from scratch using filters and plugins from both packages until i achieved the perfecto blend. I uv-mapped all of the models, then manually Painted in the shadows with Vertex Painting.
step 4 - adding the accessories
Accessories aid in the realism of the presentation. Therefore, y modeled trafic signals, Street lamps, signs, tres, and the roadway striping. Based on photos taken within the vicinity of the Project, y tried todo model the accessories todo look similar todo what you would find in that área. For instance, the majority of the tres are palm tres, and the trafic signals are black.



Using a billboard technique for the tres, y added alpha masks todo tree photos and uv-mapped them todo two crossing planes (forming an x) in Blender. For the roadway striping, y used a 3d curve as a Path and dupliverts todo copy a white rectangular plane todo represent the dashed stripes, and other 3d curves with a yellow or white plane extruded vía bev ob todo form the solid yellow or white lane lines.



I added a semi-transparent red fence representing the required right-of-way (property lines), and a semi-transparent blue plane representing the glide Path todo the adjacent runway.



step 5 - adding user-interaction
First, y would like todo give a special gracias todo randall rickert, for sharing his famous walkthrought demo -- without his Python scripts and rig, this presentation would not have ben posible. I imported señor Rickerts first-person viewer Rig and scripts into my model. With so much distance todo travel, the default settings tok todo long todo travel from one end of the Project todo the other, so i made minor tweaks todo some of the property values todo increase the viewers speed. Next i added Collisions todo specific Faces (instead of todo all of them) todo kep the frames por segundo up. Finally, y added a switch todo toggle the visibility of the right-of-way fence, which gave the client the ability todo se his property límites when he wanted, but was able todo turn them of when they got in the bien of seing other Items of interest.
the request for an animation
After i saved out the executable and sent it with the dlls todo the Project manager, he requested that i a los produce a fly-th rouge animation of about two minutes in length. This proved todo be easier than i expected. I saved a copy of my presentation and added a Path with a parented Camera.

I a los had todo modify a few of the textures (mostly the ones with alpha masks), adding them as materiales so that they would render correctly. After several Low-resolution animations testing diferent flight paths, he selected his favorite, and i rendered out the final animation at exactly two minutes in length. Uv mapping and Vertex Painting Cut the rendering time todo mere minutes.



concluding thoughts
Accurately building and rendering a Project during design (thus allowing our clients and the public todo se the finished Project while changes can still occur) aided the development based on CS principles. Real-time presentation demands are growing in the construction industry, and Blender is adequately equipped todo serve the demand.

Some helpful tools for Blender future could include a Microstation .dgn import/export script, an Infinite coordinate plane (or Even a floating coordinate plane), real-world units, and support of large high-resolution images in the real-time engine. Some helpful tools for my future include the use of Tangent space Normal Maps and the retopology tool todo lower the vertex count and shift the detail from the dtm todo the textures.



The entire presentation tok appróximately thre hundred man-hours todo create. The client loved it (the presentation), as did the Project manager (though he did not love the thre-hundred man-hours it tok todo complete), and Blender proved itself as a competitive tool in the commercial workplace.

Brian treacy.

Senior designer, pb. www.blenderart.org

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