Coordinates

The APIs for creating custom movies (‘queueMovie’) and screenshot images (‘takeScreenshot’) require that you specify a rectangular region-of-interest (ROI). The ROI defines the field-of-view of the video or image in terms of a zoom level and the location and size of the region.

The region-of-interest may be defined in either of two ways. Both methods require an ‘imageScale’ expressed in arc-seconds per pixel, and atleast one pair of X- and Y-coordinates (expressed as arc-seconds from the center of the solar disk).

The first method defines the ROI based on a pair parameters specifying the X- and Y-coordinates for the top-left (‘x1’,’y1’) and bottom-right (‘x2’,’y2’) corners of rectangle.

Image describing coordinates

An alternative method defines the ROI in terms of the X- and Y-coordinates of the center of the region (‘x0’,’y0’), coupled with the total width and height of the rectangle in pixels. Use this method if the pixel dimensions of the output are important to you. The APIs handle the translation between arc-seconds and pixels based on the value of ‘imageScale’ that you have specified.

Another image showing coordinates

Smaller values of ‘imageScale’ will produce results that appear “zoomed-in” to show more detail.

Below is a listing of the native image scales by datasource:

Image Scales by Datasource

Datasource

Dimensions (pixels)

Image Scale (arc-seconds/pixel)

PROBA2 SWAP

1024 x 1024

3.162

SDO AIA

4096 x 4096

0.6

SDO HMI

4096 x 4096

0.6

SOHO EIT

1024 x 1024

2.63

SOHO LASCO C2

1024 x 1024

11.9

SOHO LASCO C3

1024 x 1024

56.0

SOHO MDI

1024 x 1024

1.986

STEREO SECCHI EUVI

2048 x 2048

1.588

STEREO SECCHI COR1

512 x 512

15.0

STEREO SECCHI COR2

2048 x 2048

14.7

Yohkoh SXT

1024 x 1024

2.46

You are not limited to creating screenshots and movies at a datasource’s native resolution. Each image layer will be scaled to match the imageScale you have requested.