Availability of 3D Data

Replies to This Discussion

Permalink Reply by djordje on March 19, 2018 at 11:54pm

Hi Saket,

Can you attach the .gh file please?

Permalink Reply by Saket Sarupria on March 20, 2018 at 12:06am

Hi Djordje,

Thanks for the super fast response. I have changed the location to the area of interest. It shows the context partially. gh attached.

3dbuildings_NL.gh

Thanks!!

Permalink Reply by djordje on March 22, 2018 at 2:49pm

Hi Saket,

I apologize for late reply.

I opened the upper .gh file, and got the following 3d buildings:

These are all the buildings which are tagged either with specific height or number of stories.
If they do not contain that information, then a random height can be applied to each shape which represents a building. Here is the second screenshot with random height applied to other buildings:

I think the screenshot you posted in your first reply uses the same principle: random heights for buildings neither contain height nor number of stories information.
I attached your .gh file with random height parameter added to the "OSM 3D" component.

Let me know if anything was not clear.

Attachments:

• 3dbuildings_NL2.gh, 551 KB

Permalink Reply by djordje on March 25, 2018 at 9:42am

Hi Saket,

I had some free time this weekend, and tried to check some parts of Singapure with Gismo. I didn't have the exact location that you had in your initial post, so I just used the Marina Bay building's center as the location (1.283536, 103.859185). Seems like the reason why you got only that building in 3d was because "randomHeightRange_" input of the "OSM 3D" component was empty, and also the "radius_" input of the "OSM shapes" component was too short (300 meters). Once I defined the "randomHeightRange_" input and extended the "radius_" to 1200, I got the following result:

I attached the .gh file below.

If you have any other issues/recommendations/questions please let us know!

Attachments:

• 3dbuildings_NL3.gh, 551 KB

Permalink Reply by Saket Sarupria on March 25, 2018 at 11:14am

Hi Djordje,

Thank you for taking out the time to answer the query. The tool is a great help. I have a few thoughts in mind. As you said connecting the randomHeightRange_ will give the 3D geometry for the missing places. Correct me if I am wrong but the missing 3D's created are actually randomly extruded (within given dimensions, 9 to 18 for this case). I changed the  parameter from 9 to 18  to 20 to 30 and the building heights increased.

The purpose of the 3D was to use it for an outdoor CFD so I wanted the geometries up to a certain precision, hence I didn't go for the randomHeight option in the first place. It seems to me that when we open osmbuildings.org, OSM assigns a fixed default height for the buildings it doesn't have the height or no. of floors data tagged. What do you think?

Thanks again!!

Best Regards

Saket

Permalink Reply by djordje on March 25, 2018 at 11:58am

Hi Saket,

You are correct!
Gismo will check if a closed shape is tagged with "building". If it is, and it does not contain the "height" nor "building:levels" tags, its height will be randomly generated within the range of the "randomHeightRange_" input.

I do not know about osmbuildings.org specifically, but based on my limited knowledge, all these online services which generate 3d geometry by using the openstreetmap.org data, work in the same way: if height nor number of stories is not available, then the height is randomly generated for building shapes (there can be other shapes as well, not only buildings). So you may be right: it can be that osmbuildings.org may assign a single value for all of them, and not a random one. Sorry for not being able to provide a precise answer on this. I checked their github page, but it does not contain this information.

As for your CFD study: if you are not performing analysis on a larger area, you can assign the number of stories information to specific buildings in openstreetmap.org, in case they miss this data. And in case you know how many stories that buidling has. There is a tutorial on how to do this. It takes literally 5 minutes, to do it:
https://github.com/stgeorges/gismo/blob/master/resources/tutorials/...

Then you can make use of the "heightPerLevel_" input of the "OSM 3D" component: use default 3m per story or increase it if you want to.
In this way you will not only have more-less precise height for the missing buildings, but also contribute to the OSM community as a whole: every Gismo user will be able to use this information afterwards.