feat: add (i *Indexer) GenerateQuadsForPixel() to index module in @observerly/skysolve

pkg/index/indexer.go

@@ -11,8 +11,12 @@ package index
 /*****************************************************************************************************************/
 
 import (
+	"github.com/observerly/skysolve/pkg/astrometry"
 	"github.com/observerly/skysolve/pkg/catalog"
 	"github.com/observerly/skysolve/pkg/healpix"
+	"github.com/observerly/skysolve/pkg/quad"
+	"github.com/observerly/skysolve/pkg/solve"
+	"github.com/observerly/skysolve/pkg/star"
 )
 
 /*****************************************************************************************************************/
@@ -35,3 +39,63 @@ func NewIndexer(
 }
 
 /*****************************************************************************************************************/
+
+func (i *Indexer) GenerateQuadsForPixel(pixel int) ([]quad.Quad, error) {
+	// Convert the pixel index to the pixel's equatorial coordinate:
+	eq := i.HealPIX.ConvertPixelIndexToEquatorial(pixel)
+
+	// Get the radial extent of the pixel:
+	radius := i.HealPIX.GetPixelRadialExtent(pixel)
+
+	// Get the sources within the pixel's radial extent:
+	sources, err := i.Catalog.PerformRadialSearch(eq, radius)
+
+	// If we encounter an error, return it:
+	if err != nil {
+		return nil, err
+	}
+
+	// Convert the sources to stars:
+	stars := make([]star.Star, len(sources))
+
+	for _, source := range sources {
+		// For each source, we just need to sense check that the source is within the pixel:
+		eq := astrometry.ICRSEquatorialCoordinate{
+			RA:  source.RA,
+			Dec: source.Dec,
+		}
+
+		pixelIndex := i.HealPIX.ConvertEquatorialToPixelIndex(eq)
+
+		// If the source is not within the pixel, skip it:
+		if pixelIndex != pixel {
+			continue
+		}
+
+		stars = append(stars, star.Star{
+			Designation: source.Designation,
+			X:           source.RA,
+			Y:           source.Dec,
+			RA:          source.RA,
+			Dec:         source.Dec,
+			Intensity:   source.PhotometricGMeanFlux,
+		})
+	}
+
+	// We should have at least 5 sources to generate a quad:
+	if len(stars) < 5 {
+		return nil, nil
+	}
+
+	// Indexing the sources here involves storing the sources locally for future reference:
+	quads, err := solve.GenerateEuclidianStarQuads(stars, 5)
+
+	// If we encounter an error, return it:
+	if err != nil {
+		return nil, err
+	}
+
+	return quads, nil
+}
+
+/*****************************************************************************************************************/