Feature Detection Output¶
Feature detection outputs a pandas dataframe with several variables. The variables, (with column names listed in the Variable Name column), are described below with units. Note that while these variables come initially from the feature detection step, segmentation and tracking also share some of these variables as keys (e.g., the feature acts as a universal key between each of these). See Tracking Output for the additional columns added by tracking.
Variables that are common to all feature detection files:
| Variable Name | Description | Units | Type |
|---|---|---|---|
| frame | Frame/time/file number; starts from 0 and increments by 1 to N times. | n/a | int64 |
| idx | Feature number within that frame; starts at 1, increments by 1 to the number of features for each frame, and resets to 1 when the frame increments | n/a | int |
| hdim_1 | First horizontal dimension in grid point space (typically, although not always, N/S or y space) | Number of grid points | float |
| hdim_2 | Second horizontal dimension in grid point space (typically, although not always, E/W or x space) | Number of grid points | float |
| num | Number of grid points that are within the threshold of this feature | Number of grid points | int |
| threshold_value | Maximum threshold value reached by the feature | Units of the input feature | int |
| feature | Unique number of the feature; starts from 1 and increments by 1 to the number of features identified in all frames | n/a | int |
| time | Time of the feature | Date and time | object/python datetime |
| timestr | String representation of the feature time | YYYY-MM-DD HH:MM:SS | object/string |
| y | Grid point y location of the feature (see hdim_1 and hdim_2). Note that this is not necessarily an integer value depending on your selection of position_threshold | Number of grid points | float |
| x | Grid point x location of the feature (see also y) | Number of grid points | float |
| projection_y_coordinate | Y location of the feature in projection coordinates | Projection coordinates (usually m) | float |
| projection_x_coordinate | X location of the feature in projection coodinates | Projection coordinates (usually m) | float |
| lat | Latitude of the feature | Decimal degrees | float |
| lon | Longitude of the feature | Decimal degrees | float |