# Inference for Heatmaps
Dense per-pixel predictions such as depth maps are stored as a [`Heatmap`](../../api/fiftyone.core.labels.md#fiftyone.core.labels.Heatmap)
field, which you populate by passing a model to
[`apply_model()`](../../api/fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection.apply_model)
or by constructing [`Heatmap`](../../api/fiftyone.core.labels.md#fiftyone.core.labels.Heatmap) instances yourself.
The [Depth Estimation Guide](../../getting_started/depth_estimation/index.md#depth-estimation-guide) covers both paths
end to end: loading a depth model from the zoo, and running inference with a
custom Hugging Face model that isn’t zoo-compatible out of the box.