From 514371900bda86520bd4f0752adba10b4d5be2a8 Mon Sep 17 00:00:00 2001
From: Georg Hagen <git.georg.hagen@madvoxel.com>
Date: Wed, 12 Feb 2025 23:45:39 +0100
Subject: [PATCH] Expand ar frame metadata with focal length and fnumber

---
 openVulkanoCpp/AR/ArFrame.hpp                    |  6 ++++++
 openVulkanoCpp/AR/ArFrameMetadata.cpp            |  9 +++++++--
 openVulkanoCpp/AR/ArFrameMetadata.hpp            |  4 ++--
 openVulkanoCpp/AR/Provider/ArKit/ArFrameArKit.h  |  2 ++
 openVulkanoCpp/AR/Provider/ArKit/ArFrameArKit.mm | 16 ++++++++++++++++
 5 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/openVulkanoCpp/AR/ArFrame.hpp b/openVulkanoCpp/AR/ArFrame.hpp
index 3088974..40f832c 100644
--- a/openVulkanoCpp/AR/ArFrame.hpp
+++ b/openVulkanoCpp/AR/ArFrame.hpp
@@ -165,11 +165,17 @@ namespace OpenVulkano::AR
 		[[nodiscard]] float GetExposureTime() const { return frameMetadata.exposureTime; };
 
 		[[nodiscard]] float GetExposureOffset() const { return frameMetadata.exposureOffset; };
+		
+		[[nodiscard]] float GetFocalLength() const { return frameMetadata.focalLength; }
+		
+		[[nodiscard]] float GetFNumber() const { return frameMetadata.fNumber; }
 
 		[[nodiscard]] bool IsSaved() const { return m_saved; };
 
 		[[nodiscard]] const Scene::Texture* GetImageTexture();
 
+		[[nodiscard]] virtual std::string GetLensModel() const { return ""; }
+
 		void Save();
 
 		void SaveToFile(const std::filesystem::path& path, bool downsample = false);
diff --git a/openVulkanoCpp/AR/ArFrameMetadata.cpp b/openVulkanoCpp/AR/ArFrameMetadata.cpp
index 7d6e996..2af4651 100644
--- a/openVulkanoCpp/AR/ArFrameMetadata.cpp
+++ b/openVulkanoCpp/AR/ArFrameMetadata.cpp
@@ -109,6 +109,8 @@ namespace OpenVulkano::AR
 		frameData.intrinsic = {intrinsic, res};
 		camNode["ExposureDuration"] >> frameData.exposureTime;
 		camNode["ExposureOffset"] >> frameData.exposureOffset;
+		camNode["FocalLength"] >> frameData.focalLength;
+		camNode["FNumber"] >> frameData.fNumber;
 		uint64_t nanos;
 		root["Timestamp"] >> nanos;
 		frameData.timestamp = nanos;
@@ -145,6 +147,8 @@ namespace OpenVulkano::AR
     - [ {}, {}, {} ]
   ExposureDuration: {}
   ExposureOffset: {}
+  FocalLength: {}
+  FNumber: {}
 Timestamp: {}
 TimestampDepth: {}
 TrackingState:
@@ -165,7 +169,8 @@ Light:
 	camMat[0][0], camMat[1][0], camMat[2][0],
 	camMat[0][1], camMat[1][1], camMat[2][1],
 	camMat[0][2], camMat[1][2], camMat[2][2],
-	exposureTime, exposureOffset, timestamp.GetNanos(), timestampDepth.GetNanos(),
+	exposureTime, exposureOffset, focalLength, fNumber,
+	timestamp.GetNanos(), timestampDepth.GetNanos(),
 	trackingState.GetName(), lightIntensity, lightColorTemp
 );
 		return meta;
@@ -194,4 +199,4 @@ Light:
 
 		return meta.str();
 	}
-}
\ No newline at end of file
+}
diff --git a/openVulkanoCpp/AR/ArFrameMetadata.hpp b/openVulkanoCpp/AR/ArFrameMetadata.hpp
index 18ee1b4..5a1d58b 100644
--- a/openVulkanoCpp/AR/ArFrameMetadata.hpp
+++ b/openVulkanoCpp/AR/ArFrameMetadata.hpp
@@ -19,7 +19,7 @@ namespace OpenVulkano::AR
 		float exposureTime, exposureOffset, lightIntensity, lightColorTemp;
 		Math::Timestamp timestamp, timestampDepth;
 		ArTrackingState trackingState;
-		float physicalPixelSize = 0;
+		float physicalPixelSize = 0, focalLength = 0, fNumber = 0;
 
 		[[nodiscard]] std::string ToYaml() const;
 
@@ -34,4 +34,4 @@ namespace OpenVulkano::AR
 			return content[0] == '<' ? FromXML(content, length) : FromYaml(content, length);
 		}
 	};
-}
\ No newline at end of file
+}
diff --git a/openVulkanoCpp/AR/Provider/ArKit/ArFrameArKit.h b/openVulkanoCpp/AR/Provider/ArKit/ArFrameArKit.h
index d34967f..3cd7cb2 100644
--- a/openVulkanoCpp/AR/Provider/ArKit/ArFrameArKit.h
+++ b/openVulkanoCpp/AR/Provider/ArKit/ArFrameArKit.h
@@ -32,6 +32,8 @@ namespace OpenVulkano::AR::ArKit
 		ARFrame* GetArKitFrame() const { return m_arKitFrame; }
 
 		bool GetCameraImageAsJpeg(const std::function<void(const char*, size_t)>& handler) override;
+		
+		std::string GetLensModel() const override;
 
 	private:
 		ARFrame* m_arKitFrame;
diff --git a/openVulkanoCpp/AR/Provider/ArKit/ArFrameArKit.mm b/openVulkanoCpp/AR/Provider/ArKit/ArFrameArKit.mm
index c7e6738..a537725 100644
--- a/openVulkanoCpp/AR/Provider/ArKit/ArFrameArKit.mm
+++ b/openVulkanoCpp/AR/Provider/ArKit/ArFrameArKit.mm
@@ -13,6 +13,7 @@
 #import <ARKit/ARLightEstimate.h>
 #import <ARKit/ARPointCloud.h>
 #import <CoreVideo/CoreVideo.h>
+#import <ImageIO/CGImageProperties.h>
 
 namespace OpenVulkano::AR::ArKit
 {
@@ -88,6 +89,12 @@ namespace OpenVulkano::AR::ArKit
 			frameData.timestampDepth = arFrame.capturedDepthDataTimestamp;
 			frameData.trackingState = GetArTrackingState(arFrame.camera);
 			
+			if (@available(iOS 16.0, *))
+			{
+				frameData.focalLength = [(NSNumber*)[arFrame.exifData valueForKey:(__bridge NSString*)kCGImagePropertyExifFocalLength] floatValue];
+				frameData.fNumber = [(NSNumber*)[arFrame.exifData valueForKey:(__bridge NSString*)kCGImagePropertyExifFNumber] floatValue];
+			}
+			
 			return frameData;
 		}
 	}
@@ -236,4 +243,13 @@ namespace OpenVulkano::AR::ArKit
 		[image release];
 		return success;
 	}
+	
+	std::string ArFrameArKit::GetLensModel() const
+	{
+		if (@available(iOS 16.0, *))
+		{
+			return [[m_arKitFrame.exifData valueForKey:(__bridge NSString*)kCGImagePropertyExifLensModel] UTF8String];
+		}
+		return "";
+	}
 }