Miniaturized ASTRAS360 Rotary Encoder Raw Image Dataset

The Miniaturized ASTRAS360 is an absolute single-turn rotary encoder that captures data using an image sensor (stator). The encoder rotor is composed by a set of unique colored mirrors that can rotate with a single rotational degree of freedom around the image sensor. These mirrors reflect the light emitted by an LED into the image sensor passing through a slit mask place on top of it. By analyzing the color and position of the resulting light stripe, it is possible to reconstruct the angular rotation of the mirrors that generated each unique image.
To calibrate and evaluate the performance of the rotary encoder, a calibration setup was employed, which included a motorized rotational stage with an integrated rotary encoder.

Dataset Composition:
The dataset consists of 10 bits raw grayscale images in .pgm format, collected under various conditions. The RGB Bayer filter pattern on the Naneye2D image sensor follows this configuration:
Pixel (row=1, column=1) = G, Pixel (1,2) = R, Pixel (2,1) = B, and Pixel (2,2) = G.
The dataset is organized into four distinct sets.
The first two are training sets acquired at fixed incremental angular steps: one for clockwise rotation (Train_Clockwise) and the other for counterclockwise rotation (Train_CounterClockwise). These sets are intended for calibrating the rotary encoder.
The testing dataset (Test_Inference) contains images captured using randomized rotational steps and directions, designed to assess the performance of the rotary encoder.
The precision estimation dataset (Test_Precision) includes images taken at 24 equispaced angular positions, with each position containing 1000 images, aimed at estimating the precision of the rotary encoder.

File Naming Convention:
Each image file name follows this format:
“__Angle__time_.pgm”
(E.g. “3189_1_Angle_-84.32949_time_2062301894.pgm”)

The Index (e.g., 3189) represents the unique identifier for the angular position, while the ImageIndex (e.g., 1) indicates the index of the image taken at that specific angular position. The AngularValue (e.g., -84.32949) represents the angular rotation of the rotary encoder, as recorded by the motorized rotational stage, serving as the ground truth. It is reported in degree (°). The Timestamp (e.g., 2062301894) is a simple counter that starts at the beginning of every acquisition, reported in microseconds.