Segmentation Map Product

Data Product Name

DpdMerSegmentationMap

Data Product Custodian

MER

Name of the Schema File

euc-mer-SegmentationMap.xsd

Last Edited for DPDD Version

2.0

Processing Elements Creating / Updating / Using the Product

Creators:

  • MER_Detection

  • MER_Deblending

  • MER_MBCombine

  • MER_Compression

Consumers:

  • MER_Deblending

  • MER_MBCombine

  • MER_Photometry

  • MER_Compression

  • MER_Validation

Processing Function Using the Product

MER, SIR, SHE

Proposed for Inclusion in EAS/SAS

This product is proposed for inclusion in the SAS: yes.

These products contain the segmentation map produced by the object detection and deblending steps. It is useful to have them in the SAS in case scientist want to replicate the morphology and photometry calculations performed by MER.

Data Product Elements

Header:

object of type sys:genericHeader

Data:

object of type mer:merSegmentationMap

QualityFlags:

object of type dqc:sqfDpdMerSegmentationMap

Parameters:

object of type ppr:genericKeyValueParameters

Detailed Description of the Data Product

Map showing the connected pixels of the objects detected on the corresponding MER detection mosaics.

The segmentation map returned by the MER pipeline is a combination of the VIS and NIR segmentation maps produced by the MER object detection and object deblending steps. These steps run in parallel on the VIS and NIR-stack detection mosaics and produce two independent source catalogs and segmentaion maps. The combination of the segmentation maps gives preferece to VIS over NIR. The segmented pixels associated to a given VIS source are never modified, even when a NIR-only source spatially overlaps with them. In that case, the overlapping pixels will be removed from the NIR-only source segmented area. The reason for that is that SHE measurements are based only on the VIS-detected sources and should not be biased by the NIR-only sources.

The object id numbers in the segmentation map coincide with the SEGMENTATION_MAP_ID column values in the MER final catalog. SEGMENTATION_MAP_ID is computed combining the reference tile index and the source detection ids via:

(12)\[\text{SEGMENTATION_MAP_ID} = \text{TILE_INDEX} \times 10^6 + \text{SOURCE_DETECTION_ID}\]

This makes sure that the segmentation map ids are unique for a given data release. For all the sources laying outside the MER tile core area (i.e. not included in the associated MER final catalog), SEGMENTATION_MAP_ID is set to -1.

The main elements inside the MER segmentation map product are:

  • FilterList: List of filters that were used to produce the segmentation map (normally VIS and/or NIR filters).

  • WCS: The segmentation map astrometric parameters (e.g., CTYPE1, CRVAL2, CRPIX1, CD1_1).

  • ImgSpatialFootprint: The segmentation map spatial footprint.

  • TileIndex: The MER tile index.

  • PatchIdList: The sky patch ids associated to the product.

  • ObservationIdList: List of unique IDs identifying the Euclid observations that were used to generate the product.

  • CalblockIdList (optional): The calibration block ids associated to the product.

  • CalblockVariantList: The calibration block variants associated to the product.

  • ProcessingMode: The MER pipeline processing mode (e.g. WIDE, DEEP) used to generate the product.

  • DataStorage: Element that links to a FITS file containing the segmentation map data set.

  • QualityParams: The segmentation map quality parameters.

Sementation map FITS file

This FITS file contains contains information about the pixels associated to each individual source in the MER final catalog.

PRIMARY extension header keywords:

HDU PRIMARY: header

Name

Description

Value

Keywords

BITPIX

array data type

integer

CDELT1

[deg] Coordinate increment at reference

double

CDELT2

[deg] Coordinate increment at reference

double

CRPIX1

Reference pixel on this axis

double

CRPIX2

Reference pixel on this axis

double

CRVAL1

World coordinate on this axis

double

CRVAL2

World coordinate on this axis

double

CTYPE1

WCS projection type for this axis

string

CTYPE2

WCS projection type for this axis

string

CUNIT1

Axis unit

string

CUNIT2

Axis unit

string

DATASETR

The pipeline data set release

string

EQUINOX

Mean equinox

double

LATPOLE

[deg] Native latitude of celestial pole

double

LONPOLE

[deg] Native longitude of celestial pol

double

MJDREF

[d] MJD of fiducial time

double

NAXIS

number of array dimensions

integer

NAXIS1

NUMBER OF ELEMENTS ALONG THIS AXIS

integer

NAXIS2

NUMBER OF ELEMENTS ALONG THIS AXIS

integer

NIR_OFF

Offset of the NIR detected source IDs

integer

ORIGIN

Where it was done (Swarp keyword)

string

PC1_1

Coordinate transformation matrix elemen

double

PC2_2

Coordinate transformation matrix elemen

double

PIPDEFID

The pipeline definition id

string

PPLANID

The parent plan id

string

PPOID

The pipeline processing order id

string

PSWNAME

The pipeline software name

string

PSWREL

The pipeline software release

string

RADESYS

Astrometric system

string

SIMPLE

conforms to FITS standard

logical

WCSAXES

Number of coordinate axes

integer

Segmentation map quality parameters

The following list of quality parameters is calculated for each MER segmentation map. Their values can be used to select an specific subset of segmentation maps, to study global trends, or to detect potencial problems in the MER pipeline or its input products.

Quality parameter

Descriptiom

NonZeroFraction

The fraction of pixels larger than 0