Scene metadata includes a view_angle property. This article explains what the value means, why it can be negative, and which imagery sources return negative values.

What view_angle measures

view_angle is the spacecraft's across-track off-nadir viewing angle used for imaging, expressed in degrees. Nadir is the point directly beneath the satellite, so the value describes how far to the side of that point the sensor was looking when the image was captured.

An angle close to zero means the satellite was looking almost straight down. A larger angle, positive or negative, means the image was captured at more of a slant.

Why the value can be negative

The sign indicates the direction the satellite was looking, not a smaller or larger angle:

• Positive — the sensor was looking east of nadir.
• Negative — the sensor was looking west of nadir.

A value of -18 and a value of +18 therefore describe the same amount of tilt in opposite directions. In scene metadata the value falls between -25 and +25.

Which imagery returns negative values

In practice you will encounter negative view_angle values only on Landsat and RapidEye scenes in the catalog. If you work with other sources and never see a negative value, that is expected.

For the properties available on a particular item type, see the item type reference in the Data API documentation.