Neuroglancer

Neuroglancer is a Google-made viewer program that lets you freely zoom in and rotate through huge 3D image datasets inside a web browser. Just like Google Maps keeps loading smoothly down to individual roads no matter how much you zoom in, this program stitches together millions of thin brain-slice images into one giant 3D dataset and loads only the part you need at any given moment.

Data like a map of brain neural networks can reach tens of terabytes in size, making it impossible to download and open all at once. Neuroglancer solves this by slicing the data up and storing it on a server, then fetching and rendering only the portion the user is currently viewing on screen. This lets researchers navigate through a brain as if reaching in with a mouse, visually tracing the path of a single neuron.

Because it's open source, anyone can use it for free, and it's widely used as the standard tool for checking and verifying results in research that maps the neural networks of fruit flies or mice.

Neuroglancer can be opened directly in a web browser with no installation needed. Go to the public Neuroglancer page and pick one of the example datasets provided.

1. Drag the 3D view on screen with your mouse to rotate your viewpoint.
2. Scroll to zoom in and out, and watch how the fine structures change.
3. Click on an individual color-coded structure (like a single neuron) to select it — it will be highlighted on its own, making it easier to trace.

This gives you a feel for how you can explore massive 3D data piece by piece without ever downloading it.