Exporting 3D Models and 3D tiles using DJI Terra (video)

This tutorial will show you how to export 3D models and other types of files such as mosaics, and point clouds from one of the popular photogrammetry software: DJI Terra. This tutorial works for those who would like to learn how to zip and upload 3D tiles from most software.

What this tutorial covers:

• How to set up a project in DJI Terra 
• How to export 3D models (3D tiles) from DJI Terra
• How to find and zip the .json and 3D tiles folders up into one .zip file
• How to upload the data to METAGEO
• Adjust the vertical offset of the dataset
• Share the dataset

Video Transcript:

Hello, thank you for joining us on this tutorial on how to take exports from DJI Terra and put them into MetaGeo. Here we have a project that we've already started. This is a project with 281 photos, and we've already done the processing, but if we were going to start over again and do the processing from the beginning, we'd start with the aero-triangulation or the AT and we'd go ahead and process the model. In this specific one, we used a DJI Phantom and with this with this we wanted to produce 2D maps and 3D model outputs. 

The first thing we want to do is do the aero-triangulation and if you have ground control points, input them there, prior to doing the exports and then we're also going to um, when you select the 2D maps, we're going to check the coordinate system for the outputs. This will be in WGS 84 if you're not using ground control or RTK corrections but if you are using the RTK corrections or the GCPs you would go ahead and use whatever coordinate system that they were collected in. But it's important that we make sure that it is in a known coordinate system because currently MetaGeo does not support arbitrary. If you do upload a project or outputs with arbitrary coordinate systems, you will get an error in MetaGeo which says that there is no coordinate system associated with the data. 

For the 3D outputs we're going to do the same thing, make sure that we are in a known coordinate system and when we go to the outputs for our 3D models we want. We want to make sure that we have B3DM file format selected, this is 3D tiles so this will be able to be the best way to ingest it into MetaGeo and we want to make sure that if you want to have a point cloud, you can click the option above to add a point cloud exponent. From here, we're going ahead and select our area for processing, do our processing, and once we get our outputs, we'll be able to also make sure that we have our 2D maps if you would like and to get to our outputs once we're done with the processing, we're going to go ahead and click on the house icon on the top left of the home icon and then that will take us to our project and then we'll click on the folder icon down below. And once we are here we can go to models, but we also have our AT, our images, our maps. 

We will go ahead and click on the models here, and then PC, and then zero, and then Terra B3DMs. Here's our tileset.json which is our index file which tells us where all the different 3D tiles are and then the Block folder here, these are all the different 3D files. Now we are going to zip this all together using the 7zip tool. There are many tools you can use to do zips so we use 7zip, you can right click and then go to add to zip. Make sure it is a .zip and not a .7z or any other format. It must be a .zip. Now we have our file packaged and we're going to rename it so we know which project this is so we'll just write terra house demo and then we're going to MetaGeo and upload it.

Ok, now that we have logged in, we're going to go ahead and go to layers and we're going to create a new project so we can put all these outputs into them. Go to the plus icon and go to create project. We'll give this a name and just like with the upload of the file; we're going to name it the same thing and we'll go here to data; we'll click on the action button which is the three dots and then go to upload. Now we can drag and drop, or we can click on this window to open it up. But we have it right here, so we will just drag and drop it in. We're going to let it upload and while this is happening, you can go on and do other things or you can just wait for it to be completed. It will take a little while to unzip the folder on the platform and then also put the tiles in the right place, so, it takes just a little bit of processing.

Once it is done, we can go back over to our layers and then we'll be able to see the file. Ok, now it looks like it is all processed, so we're going to go ahead and double click on it and we will zoom to the layer. And we see that we are now underground. Now this happens because of the position reported by the drone or the difference in the dataset between the earth frame and the dataset reported by the software that exported it. This was a drone with no RTK and no GCPs, and so it's not uncommon for it to pop up in the wrong place as far as the altitude is concerned. We're going to go ahead and click on the icon and then the transparency and now we can see the dataset and it's under the ground here like we thought, so we're going to adjust the altitude mode uh, it's on absolute right now, we'll switch it to clamp to ground. Sometimes this works and sometimes it does not because it takes it from the center of the dataset, and we can see that it's kind of like halfway onto the surface there. So, in this case, we're going to go ahead and just double check it and turn off the transparency. And it looks like it is, yep, it is still underneath, so we're going to go ahead and switch this to a custom altitude.

With a custom altitude, we can take the dataset, use the slider, and drag it up. So, we will just go over here to the altitude mode, switch it to custom and then we'll drag over the slider and adjust it to the right height. So, up above, where it says height, you will see the numbers changing, that is meters above the original position, and you can type in a different number if you need to go higher than the slider will let you. So, there is some difference between the terrain dataset and the dataset we have collected. So that is also sometimes normal we'll have to go and double check and make sure that we have the right position so, look around, and we'll just make sure that we're happy with what we see and once we're happy, we can go ahead and save it on the top right up there. But we are just going to take a look around, and it looks pretty good.

This is how you take the outputs from Terra, the 3D models, and this is the same process for any mosaics or orthophotos and you, thank you for following along with this tutorial. If you have any questions, please reach out to us at [email protected].