> For the complete documentation index, see [llms.txt](https://docs.aeroai.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.aeroai.io/siega-web-features/other-features/split-screen-comparison.md).
# Split-Screen Comparison
The Split Screen tool lets you put two assets side by side in the same world and drag a divider to compare them. It works for two 3D Tiles assets, two
Imagery layers, or a mix of one of each. Useful for before and after looks, comparing two scans of the same site, or checking a base imagery layer against
a tileset that sits on top of it
### Open the comparison
Click the "Tile Comparison" button in the top toolbar to open the setup modal. The button shows a comparison icon and turns active when a comparison is
running.
### Pick the assets
If your library has both 3D Tiles and Imagery, switch the type at the top of the modal using the "3D Tiles" and "Imagery" buttons. The dropdowns below
will list every asset of that type from your Cesium Ion library.
Pick one asset for the "Left Side Asset" dropdown and a different asset for the "Right Side Asset" dropdown. The two have to be different. If you pick the
same asset on both sides, the modal shows a warning and the "Compare" button stays disabled.
If you only have one asset in your library, the modal shows a yellow notice telling you that you need at least two assets to compare.
#### Run the comparison
Click "Compare" to load both assets into the scene. The viewer flies to the left asset so the comparison starts framed on something you can see. A white
vertical bar appears down the middle of the viewport with the left asset on its left and the right asset on its right.
Click and drag the white bar left or right to slide the boundary across the scene. The split happens live, so you can sweep back and forth to spot
differences in a corridor, a structure, or any spot you want to check.
#### Close the comparison
Click the "Tile Comparison" button again to exit, or double click the white divider. Both assets are removed from the scene and the divider goes away.
#### Notes
The two assets need to be in the same area of the world. If you pick two 3D Tiles datasets that are more than 50 kilometers apart, the comparison will not
start and a toast will tell you the actual distance between them. Move to the same site and try again. Only assets from your Cesium Ion library are
available in the comparison dropdowns since the split rendering needs Ion sourced data.
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