Modelling on Terrain

Modelling on Terrain

Postby Rich O Brien » Thu Mar 19, 2009 10:34 pm

Hi Guys,

I've recently captured my house from Google Earth and modeled it on SU7.The file is attached.

My question is how do i get the part i modeled to sit on the sloping site that i live on? Things like the fence, house and shed are ugly when i use the stamp tool. And when i try to smoove terrain it gets messy?

If i have to start again it's fine but I'd like to know if there's a video out there that can explain what I'm trying to achieve?
There's a frontroom and a backroom....reverse faces
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Rich O Brien 

Re: Modelling on Terrain

Postby museummaker » Thu Mar 19, 2009 11:16 pm

You got a great start, it will help if you put foundations under the buildings to allow them to sit properly onto the land. Your fence posts may need to be a bit longer to accommodate some change in altitude.

Toggle the terrain on tools/GE-- then move the components of the model up and down to fit. The fence is going to be the tricky one- the rails won't run flat.

Try it out and see how it works.


Re: Modelling on Terrain

Postby AndrewS » Mon Apr 06, 2009 10:56 pm

rclub24 wrote:Hi Guys,
I've recently captured my house from Google Earth and modeled it on SU7. The file is attached. My question is how do i get the part i modeled to sit on the sloping site that i live on? Things like the fence, house and shed are ugly when i use the stamp tool. And when i try to smoove terrain it gets messy? If i have to start again it's fine but I'd like to know if there's a video out there that can explain what I'm trying to achieve?

Hi, rclub24,

Thanks for modeling for Google Earth. We always appreciate seeing more user-generated content (UGC). I have several recommendations for you, which I obtained from one of our best SU/Earth trainers and in-house modelers. I also spent quite a bit of time fixing up your model to demonstrate the topics I'll mention below so that you will understand what I mean. I'm hoping this note will help not only you, but other users in the future, which is why it's going to be far more detailed than you expected.

First and foremost, just last week, we launched a new website dedicated to UGC modeling for Earth. It has a great intro video by my friend Alex, as well as some wonderful tutorials. I think spending 10 minutes at that site will make the following instructions far clearer, so I highly recommend you go there.

Seriously, go to that site!!

And if you fancy more details, please see another site, which happens to be user-contributed.

Those are really great sites, but you wanted some advice for your specific model, so here goes.

I see five basic problems with your model so far. Some of them have to do with your terrain issues; the others are major problems that will preclude your model's acceptance into Earth if they're not fixed.
  1. The model has far too many faces.
  2. The model should be photo textured.
  3. The model currently contains a single-face terrain that needs to be removed.
  4. The model has a level straight fence and wall that doesn't touch the ground.
  5. It may be necessary to add a foundation for the house or introduce a skirt around it to match the terrain.

First, I want to address the major issues that will prevent your model from being accepted into Earth.
  • This was the most difficult thing for me to personally accept when I started Geo modeling, but the simple fact is that there's a HUGE difference between what makes for an appropriate architectural model versus what makes an acceptable model for Google Earth (GE). Primarily, GE buildings need to have as few faces as possible and they need to be photo textured. The sooner you get used to this paradigm, the sooner you'll be able to see your models accepted into GE.
  • We used to never accept models into GE that are textured with SketchUp materials, although we have begun to make exceptions. The very best way to texture your home is by photographing the outside of your home and pasting those pictures onto your home as textures. You can actually model directly from pictures using the match photo tool, or, as in your case, you can simply pin up textures onto the building you've already created. You can find tutorials for doing this online, including at the sites I mentioned above. Note that by using photo textures, there is no need to model any of the details of windows, gutters, doors, etc., which will contribute to reducing the face count, as I'll explain next. We do sometimes accept non-photo-textured models now because we have loosened the rules, but photo texturing is still preferred, so do it if you can. I just learned how to do it recently, and it's surprisingly EASY!
  • We have a pretty strict limit on how many faces a model is allowed to have for submission in Earth. This is understandable, I think, since you already know how 3D apps bog down when there are too many faces. It can be a nightmare to navigate through a densely populated city otherwise. Your starting model is already over the limit in terms of face count. Simplify, simplify, simplify! I spent a couple of hours playing with your model and reduced your face count from around 5,000 to under 1,000 by changing the fence and flattening architectural details such as the gutters, windows, doors, and framing. Instead of using geometry to model these things, you get far superior results with photo textures instead. Zoom in on the buildings in any major metropolitan city we've modeled to see what I mean (try Vancouver or New York, for instance). Even if you don't photo texture, you don't need all of those details for modeling in GE.
  • The fences increase your face count tremendously when you take the time to actually model them. The same goes for the 3D wall. The trick we use for our in-house models is to take a picture of the fence and save it as a PNG with transparency. Use Photoshop or a similar program to remove the everything except for the actual fence rails and make the background totally transparent. Then for the fence, just use a simple 2D face with no thickness, and apply the fence picture as a texture onto both sides of the face in a repeating pattern. This will make the fence appear properly from most angles (except from straight above it), and it will have several thousand fewer faces than you have now! The same goes for the brick wall. This is the single fastest way to fix your specific model's face count problems. I'll talk some more below about how your fence should be fixed to match the terrain.

Now, to address the question you asked, regarding terrain.
  • GE terrain isn't perfect. It's averaged over pretty large areas and it also doesn't always reflect reality when earth movers and backhoes have prepared land for a home's foundation. Even so, it's imperative that your model look reasonably good in the presence of that terrain.
  • First, remove that big green face you have for grass in your model at present. The reason the smooth to terrain feature is not working is that in order to work, you must begin with a surface that is comprised of many triangle faces so that each can be bent as a mesh into the shape of the terrain. With just one large face, it doesn't work. You're better off deleting your ground face than trying to fix it; I promise.
  • Let's pretend the terrain is correct, or at least close enough, and consider how to fix the problems with the house. Begin by turning off X-ray mode, then move the house downward in the blue axis until it starts to impact the terrain. Stop when that occurs. Orbit the house and use the tape measure to determine whether the terrain all the way around is close enough to make it look reasonable. In your case, unfortunately, after I did that, the front door is on the ground, but the back door has a 4-foot drop before it hits terrain. That leaves us three choices: 1) leave it alone, with the building floating; 2) create a larger foundation to prevent floating, and ignore the 4-foot drop out back; 3) build a skirt to simulate the proper terrain.
  • According to one of our in-house UGC judges, it's usually better to leave the house floating or build a foundation, than to build the skirt. This is due to several issues. 1) If the terrain in Earth is updated someday, it may fix itself; 2) if the skirt is so large as to intrude into other surrounding property, it may overlap with other UGC models in the future; 3) building a skirt requires you to do complex snapshotting of the color satellite data from Earth and paste it onto the skirt, which is complicated, and won't benefit from being updated when the satellite makes another pass in the future, so it's discouraged.
  • In your case, I would concentrate on fixing the photo texturing, redoing the fence, and lowering the house and shed so that they impact the terrain at their lowest points. After that, I'd let the rest of the building sit on an artificial foundation that impacts the terrain without hiding any of the house. This may sound silly, but if you go look in Earth at the campus of the University of Colorado at Boulder, you'll find that several buildings there are floating, due to changes in terrain that were made to GE after those models were built. In the case of the Coors Events center on that campus, you'll see that hills and other terrain were included with the model, because it was introduced before GE supported terrain properly. Some of those models now look terrible as a result, which will eventually require someone to go back and make additional fixes. Nobody wants that, which is why I suggest you just use the foundation.
  • If you just can't stand the notion of leaving your building floating in mid-air and want to ignore the warnings I gave above, then go ahead and build a skirt. I'm not going to give complete directions because you can find those on one of the sites I mentioned. But in general, you basically attach a surface of connected triangles hanging off of the building that eventually smooth out to touch the GE terrain. Then you have to go into Earth, take a screen capture (NOT a snapshot into SketchUp), to capture the color terrain, and paste it as a texture onto your skirt. It's very time-consuming and difficult for first-timers.
  • Now for the fence. You'll find I've taken a very rough shot at doing this in your model. You can either leave it or improve it as you see fit, but it illustrates the point. I started by tracing a line around your existing fence, all at one height. Then I removed the original fence you had. After that, I used "Drape" from the sandbox tools to trace that line directly onto the terrain where the fence should be. Following that, I selected all edges created by that trace and copied them 4 feet off the ground to represent the top of the fence. Then I simply drew lines at the corners to create faces. In the end, I have three faces, one for each length of fence on your property. I then applied a generic fence texture that has a transparent background, so if you look closely, you can see through the texture as needed to give the look of a real fence, even though it's just a 2-D face. After applying the texture, you want to use the position texture feature to pin the texture appropriately to make it follow the terrain. You'll note that if you make each side one large face, your texture won't fit perfectly, as evidenced by the model I modified. This is because the angle of incline is not steady across the entire span. To fix this, you could draw a line every 6 or 8 feet to represent your real split-rail fence, and customize the fit of the texture on each segment. That was too much work for me in this case, so I left it alone.

I think that's it for now. It's taken a few minutes every day for the past week to get this put together, so I want to finally get it sent out so it may be of some use. I know this is an absurdly long response, but I hope you find it helpful. Please respond on here at some point and let us know how you progress.

Best of luck modeling!
Andrew S.
SketchUp Release Engineer
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Re: Modelling on Terrain

Postby modelhead » Tue Apr 07, 2009 12:18 am

:D Wow!! Andrew. What a great piece. This exercise should be a must read for all interested in GE modeling. Thanks.


Re: Modelling on Terrain

Postby Gaieus » Tue Apr 07, 2009 10:22 am

Thanks Andrew for this post. :thumb:
I have copied your post and made a "Sticky" in the GE subforum (that we also created to encourage modelling for GE and discussions about it).

Also, Rich, I have moved your topic into the GE subforum if you don't mind (for a while, a "shadow topic" will stay here).
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Re: Modelling on Terrain

Postby Rich O Brien » Wed Apr 15, 2009 8:09 pm

thanks for the great advice and work, happy my stupid question didn't go unanswered
There's a frontroom and a backroom....reverse faces
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Rich O Brien 

Re: Modelling on Terrain

Postby ProfessoreUSA » Tue Jan 13, 2015 3:08 am


is there a way to understand how and whether GE casts and receives shadows? In my model, I see GE terrain is shaded, but shadows from buildings are flat and do not conform to the terrain. Moreover, terrain below the 0,0,0 point does not receive shadows - flat or otherwise. Moving the entire model above the 0,0,0 point (unlocking the terrain) results in nothing receiving or casting shadows.. not even building parts on each other.

I tried exploding the terrain, intersecting it with the model, .. to no avail.

Any thoughts?



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