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#: ../../../map-accuracy.rst:3
#: d4e2d7d317d34b208e768f689ad692b0
msgid "Map accuracy"
msgstr ""

#: ../../../map-accuracy.rst:5
#: 674abb654cf7448cac13ea47971e80d2
msgid "Accuracy can be defined as the degree or closeness to which the information on a map matches the values in the real world. Therefore, when we refer to accuracy, we are talking about quality of data and about number of errors contained in a certain dataset (Pascual 2011)."
msgstr ""

#: ../../../map-accuracy.rst:8
#: c23ea9314c134c8ba5671054b7e3c057
msgid "**Relative or Local accuracy**"
msgstr ""

#: ../../../map-accuracy.rst:10
#: 35f3324c29ea443497c2fdcd80a55145
msgid "Local or relative accuracy can be defined as the degree to which de distances between two points on a map correspond to the actually distances between those points in the real world."
msgstr ""

#: ../../../map-accuracy.rst:12
#: 5463e74ce3b246a4a690fcc476f95536
msgid "Relative accuracy is independent of the location of the map in the world, so a map can have a high relative accuracy (in size and shape) but its position in the world can be shifted (Figure 1)."
msgstr ""

#: ../../../map-accuracy.rst:18
#: 1d4253e1796842319b7dcbd23384343c
msgid "*Figure 1. Model showing high relative accuracy but misplaced according to its real world position*"
msgstr ""

#: ../../../map-accuracy.rst:22
#: 754655b1d1d840fbbc8c2d8980a876fb
msgid "**Absolute or global Accuracy**"
msgstr ""

#: ../../../map-accuracy.rst:24
#: e5e01529bd0c499aa456f620a7022ef5
msgid "Absolute accuracy is the accuracy of the reconstruction in relation to its true position on the planet (Pix4D 2019). Figure 2 shows a relative and absolute accurate model, as the points are correctly placed according to its real world position."
msgstr ""

#: ../../../map-accuracy.rst:30
#: 9d73ff2d96b14f37b5f6166e2baf2695
msgid "*Figure 2. Model showing high relative and absolute accuracy. Placed correctly according to its real world position*"
msgstr ""

#: ../../../map-accuracy.rst:33
#: b73218309c99474abc6119f6bfffdf61
msgid "**An Accuracy level for each project**"
msgstr ""

#: ../../../map-accuracy.rst:35
#: 1cccb608cda9412c9545ad6c5094fa64
msgid "Each project has specific accuracy needs to be met. For instance assessing the progress in a construction site or measuring an area affected by a fire does not require the use of GCP, since absolute accuracy will not impact the decision making process. In the other hand, there are tasks on which accuracy is critical, for example project compliance evaluations and land title surveying, which require a higher relative and absolute accuracy."
msgstr ""

#: ../../../map-accuracy.rst:39
#: cc37e2d221b5438597d9284f2f6b18ff
msgid "What to expect"
msgstr ""

#: ../../../map-accuracy.rst:41
#: 0a236f8f8a584a588a68484240ee6551
msgid "In general terms, one can expect the relative accuracy to be in the order of 1 to 3 times the average GSD for the dataset. And as for the absolute accuracy, one must consider that it is dependent of the GPS unit mounted in the UAV but the horizontal accuracy of a standard GPS is usually in the range of 2 to 6 meters and the vertical accuracy between 3 to 4 times the horizontal accuracy."
msgstr ""

#: ../../../map-accuracy.rst:43
#: 60659f189c6143b6bd94cb23d28105d6
msgid "When using GCP, absolute accuracy can be improved to 2.5 times GSD for the horizontal accuracy and 4 times the GSD for the vertical accuracy (Madawalagama 2016)."
msgstr ""

#: ../../../map-accuracy.rst:45
#: 7f9656e94e544adf807d480168874da7
msgid "At a GSD of 1cm, the accuracy is to that of the RTK GNSS, and is within 1:200 scales according to NSDI & FGDC mapping accuracy standards during sub-optimal conditions (Barry 2013)."
msgstr ""

#: ../../../map-accuracy.rst:49
#: 3e9dd6b536884dd38b143069f710f1ab
msgid "Aspects impacting map accuracy"
msgstr ""

#: ../../../map-accuracy.rst:51
#: fedd030db34543209cfa5ee6ef5e6196
msgid "**Weather**"
msgstr ""

#: ../../../map-accuracy.rst:53
#: dd1b686e9e6b413c96a22b6509f9d88d
msgid "Weather conditions have direct impact in the photogrammetry results, so it is important to consider cloud coverage, wind speed, humidity, sun’s altitude and other factors influencing the UAV stability and terrain illumination."
msgstr ""

#: ../../../map-accuracy.rst:55
#: dd609d1a79b64f2590b9d786fa83e5f1
msgid "**Cameras**"
msgstr ""

#: ../../../map-accuracy.rst:57
#: c3cb5f9cfee84481a72bfcb66a85f17b
msgid "Bigger and better sensors produce less noise and more clearly focused images. Also consider that rolling shutter cameras produce distorted images when the UAV is moving, so global or mechanical shutter cameras are advised for mapping jobs."
msgstr ""

#: ../../../map-accuracy.rst:60
#: e4f17c5a5c184b5691fa3a8c08bb8543
msgid "**Flight altitude**"
msgstr ""

#: ../../../map-accuracy.rst:62
#: e6a7b31d71664586a04a8fdd54f2001d
msgid "The higher the flight altitude, the larger the image footprint and GSD. The resulting larger GSD the accuracy will be decreased as there will be less detail in the recognizable features. When a smaller GSD is required an altitude of 3 to 4 times the height of the highest point is recommended."
msgstr ""

#: ../../../map-accuracy.rst:65
#: 1555b7ec782a49c6a7460f0e32d578e0
msgid "**Flight speed**"
msgstr ""

#: ../../../map-accuracy.rst:67
#: 2eb90c4a9e41400d94a560217cfc9e96
msgid "Flight speed have special effect in cameras equipped with rolling shutter, while those equipped with global or mechanical shutter tends to reduce this effect. UAV equipped with RTK positioning systems are also affected with the speed, but with hover at each photo taken, you can get very good accuracy. If instead you are moving during each photo take, the accuracy is going to be limited by two factors: the speed at which you are moving multiplied by the 1 second increments of RTK (Mather 2020)."
msgstr ""

#: ../../../map-accuracy.rst:72
#: d2ef9f75f3624fd18cc2d2e7e0f9afee
msgid "References"
msgstr ""

#: ../../../map-accuracy.rst:74
#: 9b8c9e6151824c24a592ec6ae333ff61
msgid "Barry, P., & Coakley, R. «Accuracy of UAV photogrammetry compared with Network RTK GPS.» Baseline Surveys. 2013. http://uav.ie/PDF/Accuracy_UAV_compare_RTK_GPS.pdf  (accessed 10 13, 2020)."
msgstr ""

#: ../../../map-accuracy.rst:76
#: 54475a5460a74936b892b63f462125f9
msgid "Drone Deploy. How Do I Use Ground Control Points?: A guide to using ground control points with drone mapping software. 5 8, 2017. https://www.dronedeploy.com/blog/what-are-ground-control-points-gcps/ (accessed 7 9, 2020)."
msgstr ""

#: ../../../map-accuracy.rst:78
#: 3c130fce6ff74f019cbe7244f8138545
msgid "Madawalagama, S.L., Munasinghe, N., Dampegama, S.D.P.J. and Samarakoon, L. «Low-cost aerial mapping with consumer grade.» 37th Asian Conference on Remote Sensing. Colombo, Sri Lanka, 2016."
msgstr ""

#: ../../../map-accuracy.rst:80
#: 151ceb4c0fd84418b73fd6a3717038e3
msgid "Mather, Stephen. OpenDroneMap. 30 de Marzo de 2020. https://community.opendronemap.org/t/the-accuracy-of-webodm-using-rtk-uavs/3937 (accessed 10 12, 2020)."
msgstr ""

#: ../../../map-accuracy.rst:82
#: 6f51c9cc28e6453ab07e036fa6e37a03
msgid "Pascual, Manuel S. GIS Lounge: GIS Data: A Look at Accuracy, Precision, and Types of Errors. 11 6, 2011. https://www.gislounge.com/gis-data-a-look-at-accuracy-precision-and-types-of-errors/ (accessed 07 09, 2020)."
msgstr ""

#: ../../../map-accuracy.rst:84
#: 0bc80ba7d78f4075b5ea484cdbdb767f
msgid "Pix4D. «What is accuracy in an aerial mapping project?» Pix4D. 25 de 05 de 2019. https://www.pix4d.com/blog/accuracy-aerial-mapping (accessed 10 13, 2020)."
msgstr ""

#: ../../../map-accuracy.rst:87
#: fb3f3b6f21c547389dd446af2ff2d1e0
msgid "`Learn to edit <https://github.com/opendronemap/docs#how-to-make-your-first-contribution>`_ and help improve `this page <https://github.com/OpenDroneMap/docs/blob/publish/source/map-accuracy.rst>`_!"
msgstr ""
