Fixing TerrainLayer Zooming & Draping In Deck.gl

Hey guys, let's talk about a tricky issue with TerrainLayer and TerrainExtension in deck.gl. I've been wrestling with it, and it seems like a few things are happening that we need to sort out. The goal? To get super high-resolution zooming working smoothly, eventually even supporting those awesome Google Photorealistic 3D Tiles. Let's break down the problem and find some solutions. This is where we will discuss the TerrainLayer zooming, as well as the problems with TerrainExtension draping.

The Core Problem: Zooming Fragmentation

So, here's the deal. When you try to zoom in super close, especially with a high maxZoom setting, the draped layers start to fragment. This means the details you're trying to highlight on the terrain get hidden, which is the opposite of what we want. This problem specifically arises with the TerrainExtension draping functionalities. It's like the layers are breaking apart as you zoom in, which definitely isn't ideal.

I created a CodePen to demonstrate the issue. Take a look; you'll see what I mean. If you restrict the maxZoom to something like 14, the fragmentation disappears. The problem is that the drawn texture doesn't update, and it does not scale the content correctly. Unfortunately, this isn't a viable workaround for the app, because we want to zoom as closely as possible. The aim is to make the TerrainExtension work like a charm across all zoom levels, especially with layers like PathLayer and TripsLayer. That's where we're headed. The problem specifically arises with the TerrainExtension draping functionalities. It's like the layers are breaking apart as you zoom in, which definitely isn't ideal. This problem makes it so we are unable to display the content to its fullest potential and scale with the zoom. I'm hoping we can find a solution that works so we can get rid of these fragmentation problems.

Diving into the Details: Reproducing the Issue

To fully understand the problem, let's look at how to reproduce it. I've set up a CodePen to showcase the issue. This allows us to share code and make sure we can test. I recommend the following steps:

1. Open the CodePen: Head over to the provided CodePen link to see the issue in action. This is the best way to see the problem.
2. Zoom In: Start zooming in to observe the fragmentation. You'll notice how the draped layers start to break up as you zoom in. This is where you can see the problem and how it impacts the content.
3. Adjust maxZoom: Try changing the maxZoom property. You'll see that a lower value prevents the fragmentation but also limits the zoom. It's important to experiment with the maxZoom value to understand how it affects the content.
4. Observe the Behavior: Pay close attention to how the TerrainExtension interacts with the PathLayer (or other layers). The goal is to get this interaction to work well across all zoom levels. This helps us ensure that the displayed content scales correctly.

By following these steps, you'll be able to see the issue first-hand. This will help us understand the problem. It is important to reproduce the issue so that we can find the best solution possible.

Understanding the Environment

It's important to know the environment so that we can resolve the problem. The issue was observed in the following settings:

• Framework Version: The issue has been observed in deck.gl versions 8.9.0 (CodePen) and 9.1.11 (local repository). This is where the code was tested, so knowing these versions will help reproduce the problems.
• Browser: Chrome was used to test the issue. Knowing that Chrome was used is important, because some browsers may have unique behaviors.
• Operating System: MacOS Tahoe was the operating system used. This is another important factor in the testing, because different operating systems may have different ways to show the content.

These details help to ensure that the issue can be properly replicated and addressed. Providing these details is key in order to help solve the problem.

Expected Behavior: Harmony Across Zoom Levels

What we ultimately want is for the TerrainExtension to play nicely with all zoom levels. Specifically, we want the PathLayer (and TripsLayer) to work smoothly, regardless of how far you zoom in or out. Basically, the draped layers should remain intact and display all the details correctly at every zoom level. Think of it as seamless integration, so that the content is displayed in the best way possible. This will make the user experience the best it can be.

Imagine you're tracing paths across a terrain. You should be able to zoom in super close to see every detail without the layers breaking apart. That's the dream. It will allow you to see the content at its finest.

Acknowledgment and Gratitude

Big thanks to the amazing folks who helped me along the way. Discussions with @akre54, who pointed me in the right direction, and a recommendation for help from @felixpalmer. The contributions and recommendations of these deck.gl experts are helping in our journey. I really appreciate the assistance from everyone involved. It's great to have such a supportive community.

Troubleshooting Steps and Potential Solutions

Here are some of the steps we can take to fix the problem:

1. Investigate maxZoom: First, we will examine how the maxZoom property impacts the fragmentation. This includes how it interacts with the different zoom levels and helps to determine if there are any limitations. Testing different values will help us better understand the problem.
2. Inspect Layer Interactions: We need to dig into how TerrainExtension interacts with layers like PathLayer and TripsLayer. This will help us to understand if there are any conflicts. Understanding these interactions is important to making sure that they work together correctly.
3. Shader Analysis: We can explore the shaders used by TerrainExtension. This involves checking for any potential issues related to the zooming. This can help pinpoint any points in the code that are causing problems.
4. Optimization: Finally, we can try to optimize the rendering process. This will ensure that the layers and textures are properly displayed. Optimizing the rendering process can improve the user experience.

By taking these steps, we can hopefully identify the root cause of the fragmentation and get those draped layers working harmoniously across all zoom levels. The goal is to make the experience smooth and enjoyable for everyone.

Conclusion: Towards Seamless Terrain Visualization

We're aiming to create a seamless terrain visualization experience in deck.gl, where zooming in doesn't mean sacrificing detail. By addressing the TerrainLayer zooming and TerrainExtension draping issues, we'll be able to create applications. This will help us to get super high-resolution imagery and detailed path visualizations. I hope these steps will help, and together, we can overcome this challenge and build something awesome. Let's get those layers draping perfectly!