Thermal infrared imagery digital maps of surface geothermal activity for residential areas of Rotorua city

Summary

1. A total of 65 thermal infrared (TIR) images covering the Ohinemutu, Kuiraii Park and Sophia Street/Arikikapakapa areas were digitised for this project from the original videotape recorded over Rotorua City on the evening of 1 March 1990.

2. Deleterious vibration and intensity variation effects present in the 1 IR imagery were identified and corrected to a good standard.

3. Over 20 Tilt images for each of the study areas were rectified to NZMG co-ordinates by registering them to corresponding orthophotographs provided by the Rotorua District Council. Average total root mean square (RMS) errors associated with this process ranged from negligible to -4-6111. or -2.8-4.2 iii in N-S and E-W directions.

4. A single Tilt "image" covering each study area was created by digitally mosaicking 20images for Ohinemutu, 17 for Kuirau Park, and 20 for Sophia Street/Arikikapakapa. Careful mosaicking reduced the rectification errors and removed most of the questionable intensity areas in them.

5. The mosaicked images fur each area were "calibrated" using ground control data obtained during the survey. Uncertainties in the imagery caused by scanner vibration. various intensity variations and assumptions required to conduct calibration. prevented confident absolute temperatures being obtained.

6. The project was successfully completed by using the calibrated images to produce (1) a detailed surface thermal intensity distribution map and (2) a colour thematic map that shows six thermal intensity levels above ambient for each area.

7. The final product thermal intensity distribution maps. rectified to NZMG co-ordinates and compatible with both ARC/VIEW and ARC/INFO GIS, are included on the CD-ROM accompanying this report.