Overview

• Use drone's images from the same place, taken with both RGB and Thermal (FLIR) DJI cameras. Resolution of FLIR images is limited (640x512 pixels)
• Merge these images into one common reference system
• Produce a geometry from the RGB images and create two textured meshes, one for each modality.

Getting Started

• Download this dataset: Thermal_Imagery_IRDataset.7z

Create RGB Model

• Create a first block with RGB images

 

Process RGB Aerotriangulation (AT)

• Take note of the Spatial reference system

Create Infrared Model

• Create a block with IR images
  • If the camera is not recognized, right click on Photogroup and select Get camera model from database

• Search for FLIR and select DJI FLIR 9mm 640x512

• Examine your infrared images and find 3 locations that can be identified. For example, in this project, we can choose 3 corners of the roof line.
  
  • For now, you are just thinking about the locations and will define them later
  • Corners of pavement and grass also work well

Add Tie Points

• Add 3 user tie points and define them in at least 3 RGB images for each one.

• Export the points a text file

Create Survey Points

• Create Survey Points from previously exported User Tie Point
  • Now within your Infrared block, Select the Survey Tab
  • Import The Survey Points that you create from your RGB block using the Custom text format wizard.
    
    

• • Set Spatial reference system to WGS 84, orthometric height (MSL) geoid EGM96

• • Define each column as shown

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  • and run AT with positioning mode 'Use Survey Points for rigid registration.'

 

• Merge blocks

Create a reconstruction and produce two meshes: one textured with visible colours, the other one with thermal imagery

 

   

Measure Temperature

• Measurements: since colour equalization did not alter thermal images, their original grey level, from 0 to 255 is preserved. The measurement tool of the viewer can display this level:
  
  • So far, ITwin Capture Modeler does not know how to convert these values into a real temperature. This conversion depends on the camera vendors and models. If there exist a known affine transformation between these values and real temperature, one can manually edit the metadata.xml file located in the production to define this relationship.
  • This metadata.xml file will be used by ITwin Capture Modeler Viewer which will modify the way it displays temperature.

Settings for Celsius

 

Settings for Fahrenheit