PIX4D Training:

Average Ground Sampling Distance (GSD) 5.32 cm / 2.10 in

Mean Reprojection Error [pixels] 0.159

Common products:

  • point cloud

  • 3d mesh

  • orthomosaic ….

Steps:

  1. project top left corner

  2. create new project

  3. name + folder

  4. add images

  5. next

  • coordinates and geodata load in

  1. select output coordinate system

Georeferencing:

Why?

  • situates the project

  • makes measurements

  • provides scale and orientation to the project

  • imporves processing time (image geotag)

  • reduced error accumulation (GCP)


Ground Control Point (GCP):

characteritisc features with known, accurate coordinates

can use:

  • GPS station

  • total station

  • online - aka google maps

Image Geotags:

GPS coordinates for each image (EXIF or txt file)

  • consumer grade GPS

  • RTK GPS logger


How many GCP:

  • Min 3

  • Recommened 5 to 8 for project,

  • well spread out, near fetures of interest

  • not in a staight line

  • if more, convert to check point for accuracy assessment


survey grade = 0.02 m

consumer grade = 5-10 m

maps services (google maps/earth):

  • urban area: few m

  • rural area: 10-20m

these are typical values. they might change from image to image.


*0.5 for raster

  • you can create GCP manually online by marking or

  • import GCPs

Measurements:

Reconstruction is of good quality

Ground Control Points:

  • Well spread

  • Around Point of interest

or

Scale constraint:

  • around point of interest

  • 2 or 3 to average the clicking error