Added support for DJI distortion (#21)

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.1)
+cmake_minimum_required(VERSION 3.10)
 
 project(TinyEXIF)
 include(GNUInstallDirs)

TinyEXIF.cpp

@@ -32,18 +32,18 @@
 */
 
 #include "TinyEXIF.h"
-
-#ifndef TINYEXIF_NO_XMP_SUPPORT
-#include <tinyxml2.h>
-#endif // TINYEXIF_NO_XMP_SUPPORT
-
-#include <cstdint>
+#include <cstddef>
 #include <cstdio>
 #include <cmath>
 #include <cfloat>
 #include <vector>
 #include <algorithm>
 #include <iostream>
+#include <sstream>
+
+#ifndef TINYEXIF_NO_XMP_SUPPORT
+#include <tinyxml2.h>
+#endif // TINYEXIF_NO_XMP_SUPPORT
 
 #ifdef _MSC_VER
 namespace {
@@ -1114,8 +1114,19 @@ int EXIFInfo::parseFromXMPSegmentXML(const char* szXML, unsigned len) {
 				if (element == NULL || (szAttribute = element->GetText()) == NULL)
 					return false;
 			}
-			value = strtoul(szAttribute, NULL, 0); return true;
-			return false;
+			value = strtoul(szAttribute, NULL, 0);
+			return true;
+		}
+		// same as previous function but with std::string
+		static bool Value(const tinyxml2::XMLElement* document, const char* name, std::string& value) {
+			const char* szAttribute = document->Attribute(name);
+			if (szAttribute == NULL) {
+				const tinyxml2::XMLElement* const element(document->FirstChildElement(name));
+				if (element == NULL || (szAttribute = element->GetText()) == NULL)
+					return false;
+			}
+			value = std::string(szAttribute);
+			return true;
 		}
 	};
 	const char* szAbout(document->Attribute("rdf:about"));
@@ -1128,6 +1139,28 @@ int EXIFInfo::parseFromXMPSegmentXML(const char* szXML, unsigned len) {
 		ParseXMP::Value(document, "drone-dji:CalibratedFocalLength", Calibration.FocalLength);
 		ParseXMP::Value(document, "drone-dji:CalibratedOpticalCenterX", Calibration.OpticalCenterX);
 		ParseXMP::Value(document, "drone-dji:CalibratedOpticalCenterY", Calibration.OpticalCenterY);
+		std::string dewarpData;
+		ParseXMP::Value(document, "drone-dji:DewarpFlag", Distortion.DewarpFlag);
+		ParseXMP::Value(document, "drone-dji:DewarpData", dewarpData);
+		std::vector<double> distortionParams;
+		size_t pos = dewarpData.find(';');
+		if (pos != std::string::npos) {
+			std::stringstream ss(dewarpData.substr(pos + 1));
+			std::string item;
+			while (std::getline(ss, item, ',')) {
+				distortionParams.push_back(std::stod(item));
+			}
+		}
+		// The DewarpData string has the following format:
+		// date;Fx,Fy,Cx,Cy,K1,K2,P1,P2,K3
+		// , where Fx, Fy are focal lengths in pixels, Cx, Cy are optical center offsets from the image center in pixels
+		if (distortionParams.size() == 9) {
+			Distortion.K1 = distortionParams[4];
+			Distortion.K2 = distortionParams[5];
+			Distortion.P1 = distortionParams[6];
+			Distortion.P2 = distortionParams[7];
+			Distortion.K3 = distortionParams[8];
+		}
 	} else
 	if (0 == strcasecmp(Make.c_str(), "senseFly") || 0 == strcasecmp(Make.c_str(), "Sentera")) {
 		ParseXMP::Value(document, "Camera:Roll", GeoLocation.RollDegree);
@@ -1165,6 +1198,17 @@ int EXIFInfo::parseFromXMPSegmentXML(const char* szXML, unsigned len) {
 
 #endif // TINYEXIF_NO_XMP_SUPPORT
 
+bool EXIFInfo::Calibration_t::hasCalibration() const {
+	return FocalLength > 0.0 && OpticalCenterX > 0.0 && OpticalCenterY > 0.0;
+}
+
+bool EXIFInfo::Distortion_t::hasDewarpFlag() const {
+	return DewarpFlag != UINT32_MAX;
+}
+bool EXIFInfo::Distortion_t::hasDistortion() const {
+	return K1 != 0.0 || K2 != 0.0 || P1 != 0.0 || P2 != 0.0 || K3 != 0.0;
+}
+
 void EXIFInfo::Geolocation_t::parseCoords() {
 	// Convert GPS latitude
 	if (LatComponents.degrees != DBL_MAX ||
@@ -1210,6 +1254,9 @@ bool EXIFInfo::Geolocation_t::hasOrientation() const {
 bool EXIFInfo::Geolocation_t::hasSpeed() const {
 	return SpeedX != DBL_MAX && SpeedY != DBL_MAX && SpeedZ != DBL_MAX;
 }
+bool EXIFInfo::Geolocation_t::hasAccuracy() const {
+	return AccuracyXY != 0 && AccuracyZ != 0;
+}
 
 bool EXIFInfo::GPano_t::hasPosePitchDegrees() const {
 	return PosePitchDegrees != DBL_MAX;
@@ -1306,6 +1353,14 @@ void EXIFInfo::clear() {
 	GeoLocation.LonComponents.seconds   = 0;
 	GeoLocation.LonComponents.direction = 0;
 
+	// Distortion
+	Distortion.DewarpFlag = UINT32_MAX;
+	Distortion.K1 = 0;
+	Distortion.K2 = 0;
+	Distortion.P1 = 0;
+	Distortion.P2 = 0;
+	Distortion.K3 = 0;
+
 	// GPano
 	GPano.PosePitchDegrees = DBL_MAX;
 	GPano.PoseRollDegrees = DBL_MAX;

TinyEXIF.h

@@ -251,7 +251,21 @@ public:
 		double FocalLength;             // Focal length (pixels)
 		double OpticalCenterX;          // Principal point X (pixels)
 		double OpticalCenterY;          // Principal point Y (pixels)
+		bool hasCalibration() const;    // Return true if FocalLength, OpticalCenterX, OpticalCenterY are available (nonzero)
 	} Calibration;
+	struct TINYEXIF_LIB Distortion_t { // Lens distortion information
+		uint32_t DewarpFlag;            // Dewarp flag - indicates whether undistortion has been applied to the image
+										// UINT32_MAX: flag missing from EXIF data
+										// 0: no dewarp (raw image) - the image is distorted, should also have coefficients
+										// 1: dewarp applied (undistorted image)
+		double K1;
+		double K2;
+		double P1;
+		double P2;
+		double K3;
+		bool hasDewarpFlag() const; // Return true if DewarpFlag is available
+		bool hasDistortion() const; // Return true if any of K1, K2, P1, P2, K3 are available
+	} Distortion;
 	struct TINYEXIF_LIB LensInfo_t {    // Lens information
 		double FStopMin;                // Min aperture (f-stop)
 		double FStopMax;                // Max aperture (f-stop)
@@ -302,6 +316,7 @@ public:
 		bool hasRelativeAltitude()const;// Return true if (rel_alt) is available
 		bool hasOrientation() const;    // Return true if (roll,yaw,pitch) is available
 		bool hasSpeed() const;          // Return true if (speedX,speedY,speedZ) is available
+		bool hasAccuracy() const;       // Return true if (accuracyXY,accuracyZ) is available
 	} GeoLocation;
 	struct TINYEXIF_LIB GPano_t {           // Spherical metadata. https://developers.google.com/streetview/spherical-metadata
 		double PosePitchDegrees;        // Pitch, measured in degrees above the horizon, for the center in the image. Value must be >= -90 and <= 90.

main.cpp

@@ -130,5 +130,11 @@ int main(int argc, const char** argv)
 		std::cout << "GPano.PosePitchDegrees " << imageEXIF.GPano.PosePitchDegrees << "\n";
 	if (imageEXIF.GPano.hasPoseRollDegrees())
 		std::cout << "GPano.PoseRollDegrees " << imageEXIF.GPano.PoseRollDegrees << "\n";
+	if (imageEXIF.Distortion.hasDewarpFlag())
+		std::cout << "Distortion.DewarpFlag " << imageEXIF.Distortion.DewarpFlag << "\n";
+	if (imageEXIF.Distortion.hasDistortion())
+		std::cout << "Distortion [K1 K2 P1 P2 K3] " << std::setprecision(6)
+		          << imageEXIF.Distortion.K1 << " " << imageEXIF.Distortion.K2 << " " << imageEXIF.Distortion.P1
+		          << " " << imageEXIF.Distortion.P2 << " " << imageEXIF.Distortion.K3 << "\n";
 	return EXIT_SUCCESS;
 }