EarthMeshHoudini

Generate real world meshes in Houdini using the Google API.

Prerequisites

Google Cloud Account

You need a google account to be able to use this HDA. The process is easy:

1. To begin click-on this link.
2. Click Start free on the top left corner, you need to be logged in with a google account like gmail. If start free is not present it's probably because you already use google cloud, so instead link on Console on the top right (should be here if you are logged), then click on the combo box on the top left, and you could jump to the step 6.
3. Fill your country, your organization description (I personally put Business idea / startup idea) and agree to terms of service and click Continue.
4. Fill your personal information and your credit card (but you should not be charged if you don't overuse it, the free tier is relatively big and the Tile API is supposed to be free for a year, but check it yourself) and click Continue.
5. Fill the survey.
6. Click on the top-right on My First Project, and them click on Create a new project.
7. Give-it a name (I personally called it Geospacial) and choose no organization a press Create.
8. Click on the Hamburger Icon on the top right. choose API and Service then Library.
9. Search for Map Tiles API and Enable it (It should give you a key at this Stage Keep it and do not share it with anyone).
10. Search for Maps Elevation API and Enable it.
11. You can test if your key supports the Map Tiles API by trying this link on your favorite browser https://tile.googleapis.com/v1/3dtiles/root.json?key=YOUR_API_KEY, replace YOUR_API_KEY by your key, if you see an error message it's not good, and you need to check again your account.
12. You can test if your key supports the Elevation API by trying this link on your favorite browser https://maps.googleapis.com/maps/api/elevation/json?locations=39.7391536%2C-104.9847034&key=YOUR_API_KEY, replace YOUR_API_KEY by your key, if you see an error message it's not good, and you need to check again your account.

Additional Python Packages

You need to add 2 additional python packages, pygltflib to load gltf files, DracoPy to uncompress mesh compression from google used by the 3D tiles.

• Launch Houdini.
• Go to the top menus Windows >> Shell.
• Type hython -m pip install pygltflib to install the pygltflib.
• Type hython -m pip install DracoPy to install DracoPy.
• Quit Houdini.
• The 2 packages are installed, your are good to go to the next step.

Note: Some user had to install PIP, in this case follow the instruction here.

SideFX Labs

I use this node from Labs, so you need to install the Labs Package.

• Launch the Houdini Laucher and install the Labs/Packages.

(Optional) Increase the viewport material setting

If you don't do that, most of the things you will see in the viewport won't be textured. It's optional but very recommended.

• Open the Display Option.
• Go to the Material tab.
• Increase the Single Object Material Limit to a big number like 5000.
• instantiate a new Scene Viewer or quit and restart Houdini.

How to use the HDA

EarthMesh

Place the EarthMesh node in your scene.

Configure the node with the right parameter for your usage. I suggest you start with the parameters in the screenshot, or use the test scene EarthMesh_Test.hip at the root of the repo.

• Google API Key Copy your key here, you can replace the whole $Google_Cloud_Api_Key string with your key, or set an environment variable named Google_Cloud_Api_Key and set your key as value.
• Cache path Path of the temp cache (recommended value $HIP/Cache). Make sure this folder exists on your drive
• Latitude Latitude of the area you want to capture, i usually do a copy-paste from google map.
• Longitude Longitude of the area you want to capture, i usually do a copy-paste from google map.
• Min Error The highest definition you want to use for your mesh, smaller number means higher definition. 2 is presently the best definition, maybe one day google will enrich their server with more detailed meshes.
• Max Error The lowest definition you want to use for your mesh, smaller number means higher definition. 60000 is presently the worst definition.
• Min Dist If the bounding box is below this distance, the resolution will be set to the MinError resolution.
• Max Dist If the bounding box is farther from this distance the resolution will be set to the MaxError resolution. If the distance is in-between the chosen resolution will be an interpolation between MinError and MaxError
• Max Meshes Limit the number of GLB loaded, to avoid scraping the whole google database and explode your budget and also avoid being trapped in an infinite loop.
• Show Bounding Boxes It's mainly an option I used to debug, it builds a mesh with the bounding boxes instead of the actual mesh from google.
• Remove Skirt Skirts are small polygons used to avoid gaps between meshes. For most common usage it's better to keep polygons, but if you want to display your mesh in additive or generate a point cloud, this option might be useful.
• Clear Cache Press this button to clear your cache.

Be patient it takes couple of minutes to dowwnload and build the meshes.

1 unit in Houdini, is 1 meter in real live, the X axis point to the North, the Z axis point to the East.

TextureAtlas

Using countless lots of 256x256 textures, it is not practical and also slow to render (Too many draw calls), this node is here to help you..

• TextureDirectory Folder where all the atlas textures will be exported. Make sure this folder exists on your drive
• Prefix All the texture filename will start with this.
• Padding Number of pixels used to separate the little textures block inside the big texture. Useful to avoid seams when using mipmaps. Too big value will reduce the resolution of the texture.
• Extension File format used to export atlas textures.
• Max Atlas Size Dimension of generated atlas textures. (don't use a size bigger than 8192 for Unreal)

If you don't want to see pixelated textured in your houdini viewport, you probably want to uncheck Limit Resolution on the Texture tab of Display Option .

Trouble shooting

To optimize and also limit the number of requests to the google cloud, I use a cache in a folder specified in the digital asset. If a file in the cache is corrupted (it's never happened to me, but for example if Houdini crashes or is killed while generating the mesh) it might result in various issues like crashing Houdini, if you suspect the cache to be the source of your problems don't hesitate to delete all the files inside. There is nothing in the cache that can't be downloaded again from the cloud.

Know issues

There are currently a few warnings related to the labs's QuickMaterials node just after loading the HDA. I'll do some follow-up with SideFX, and figure out what the solution is.

Planified Improvement

• Make the download phase interruptible, presently you only rely on the max_meshes parameter to avoid a very long wait or an infinite loop while experimenting with LOD parameters. (Done)
• Optimize the mesh construction, I already optimized this part a lot. I will try to optimize it more. I am open to suggestions. (Done)
• Probably a ton based on your feedback.

Warning

I am not a legal expert, but the meshes from google are copyrighted. Be careful when using them in a project.