Add magnitude filter to plate solver

kylecorry31 · Dec 22, 2024 · cb8ffff · cb8ffff
1 parent cc7acdb
commit cb8ffff
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Showing 3 changed files with 11 additions and 6 deletions.
diff --git a/src/main/kotlin/com/kylecorry/sol/science/astronomy/Astronomy.kt b/src/main/kotlin/com/kylecorry/sol/science/astronomy/Astronomy.kt
@@ -678,9 +678,10 @@ object Astronomy : IAstronomyService {
         approximateLocation: Coordinate?,
         tolerance: Float,
         minMatches: Int,
-        numNeighbors: Int
+        numNeighbors: Int,
+        minMagnitude: Float
     ): List<DetectedStar> {
-        return PlateSolver(tolerance, minMatches, numNeighbors).solve(
+        return PlateSolver(tolerance, minMatches, numNeighbors, minMagnitude).solve(
             readings,
             time,
             approximateLocation ?: Time.getLocationFromTimeZone(time.zone)

diff --git a/src/main/kotlin/com/kylecorry/sol/science/astronomy/IStarService.kt b/src/main/kotlin/com/kylecorry/sol/science/astronomy/IStarService.kt
@@ -35,7 +35,8 @@ interface IStarService {
         approximateLocation: Coordinate? = null,
         tolerance: Float = 0.04f,
         minMatches: Int = 5,
-        numNeighbors: Int = 3
+        numNeighbors: Int = 3,
+        minMagnitude: Float = 4f
     ): List<DetectedStar>
 
 }
diff --git a/src/main/kotlin/com/kylecorry/sol/science/astronomy/stars/PlateSolver.kt b/src/main/kotlin/com/kylecorry/sol/science/astronomy/stars/PlateSolver.kt
@@ -6,11 +6,13 @@ import com.kylecorry.sol.time.Time
 import com.kylecorry.sol.units.Coordinate
 import java.time.ZonedDateTime
 import kotlin.math.absoluteValue
+import kotlin.math.max
 
 internal class PlateSolver(
     private val tolerance: Float = 0.04f,
     private val minMatches: Int = 5,
-    private val numNeighbors: Int = 3
+    private val numNeighbors: Int = 3,
+    private val minMagnitude: Float = 4f
 ) {
 
     fun solve(
@@ -85,7 +87,8 @@ internal class PlateSolver(
 
         // Remove stars that are way below the horizon
         // TODO: Also remove stars that are way out of sight based on the input readings
-        val starReadings = stars.map {
+        // NOTE: Magnitude is inverted, so lower is brighter
+        val starReadings = stars.filter { it.magnitude <= minMagnitude }.map {
             it to AltitudeAzimuth(
                 Astronomy.getStarAltitude(it, time, approximateLocation, true),
                 Astronomy.getStarAzimuth(it, time, approximateLocation).value
@@ -168,7 +171,7 @@ internal class PlateSolver(
 
     private fun getConfidence(v1: FloatArray, v2: FloatArray): Float {
         val percentDifferences = v1.zip(v2).map { (a, b) ->
-            (a - b).absoluteValue / ((a + b) / 2)
+            (a - b).absoluteValue / max(a, b)
         }
 
         return 1 - percentDifferences.max()