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Using digital repeat photography for monitoring the regrowth of a clear-cut area

Forslund, Ludvig LU (2014) In Student thesis series INES NGEK01 20132
Dept of Physical Geography and Ecosystem Science
Abstract (Swedish)
Sammanfattning
Digitala övervakningskameror har tidigare använts inom fenologisk forskning för att kunna mäta grönskan i trädkronor. Man har under en längre tid kunnat koppla lövträdets årscykel till klimatförändringar och på så sätt haft ett starkt incitament att studera sambandet. I denna uppsats utforskas möjligheten att applicera metoden med digitalkameror på ett nyligen kalhugget område för att se om man kan mäta återväxten under tre års tid (2011-2013). Genom att extrahera pixelvärden och beräkna grönskan kan man under de tre växtsäsongerna studera en signifikant ökning i markvegetation. Under arbetet har digitalkamerorna jämförts med sensordata, så kallad NDVI, för att studera huruvida metoden kan mäta sig med mer precis och... (More)
Sammanfattning
Digitala övervakningskameror har tidigare använts inom fenologisk forskning för att kunna mäta grönskan i trädkronor. Man har under en längre tid kunnat koppla lövträdets årscykel till klimatförändringar och på så sätt haft ett starkt incitament att studera sambandet. I denna uppsats utforskas möjligheten att applicera metoden med digitalkameror på ett nyligen kalhugget område för att se om man kan mäta återväxten under tre års tid (2011-2013). Genom att extrahera pixelvärden och beräkna grönskan kan man under de tre växtsäsongerna studera en signifikant ökning i markvegetation. Under arbetet har digitalkamerorna jämförts med sensordata, så kallad NDVI, för att studera huruvida metoden kan mäta sig med mer precis och konventionell teknik. Detta har den visat sig kunna där de digitala kamerorna, i vissa fall, visat sig vara mer känsliga för hastiga variationer i grönska än de parallella sensormätningarna.
Forskning har bevisat att det största läckaget av markbundet kol sker under de inledande åren efter skogsfällning. Detta kol har skogens jordar tidigare förvarat och konserverat, men efter fällning läcker det ut i atmosfären som koldioxid. Läckaget har också visat sig ha ett starkt samband med den initiala återväxten av markvegetation på kalhygget. Digitalkamerorna skulle således kunna användas för att studera relationen. I denna uppsats diskuteras därför vidare användning av metoden inom skogsforskning och industri.
En annan applicering, i form av vegetationsövervakning, undersöks också i denna uppsats där digitalkamerorna skulle kunna vara till stor hjälp inom skogsindustri och skogsvård. Målet med denna uppsats har alltså varit att utforska användningen av digitala kameror för att studera möjligheten att övervaka återväxten av ett kalhygge. (Less)
Abstract
Abstract
The use of inexpensive digital cameras in phenological research has been acclaimed since results in previous research have shown that they are reliable and precise in measuring greenness of vegetation. The work of this thesis aims to broaden the applicability by studying how well the method performs when measuring the regrowth of a clear-cut area. This is needed to complement existing research that primarily uses the technique to study phenology. Data acquisition from the digital images was carried out with the use of chromatic coordinates in comparison to parallel measurements of sensor-based NDVI. These time series were analyzed through correlations, measuring the linear dependency and covariance. The results show significant... (More)
Abstract
The use of inexpensive digital cameras in phenological research has been acclaimed since results in previous research have shown that they are reliable and precise in measuring greenness of vegetation. The work of this thesis aims to broaden the applicability by studying how well the method performs when measuring the regrowth of a clear-cut area. This is needed to complement existing research that primarily uses the technique to study phenology. Data acquisition from the digital images was carried out with the use of chromatic coordinates in comparison to parallel measurements of sensor-based NDVI. These time series were analyzed through correlations, measuring the linear dependency and covariance. The results show significant similarities between the two measured time series and the increase in vegetation denseness during the studied period (2011-2013). It is also shown that the chromatic coordinates are more sensitive to variations in chlorophyll greenness than NDVI.
These results, together with previous research, show that the digital camera is a valuable tool that is possible to apply to forest research and industry. Studies of clear-cut areas have shown that soil carbon release is strongly dependent on initial vegetation, a relationship that is possible to study following the results of this thesis. However, more research is needed to calibrate the method for measurements in different forest types and climate zones, before this is reality. The use of ground-level reference panels are also analyzed but fails to provide the reliable information needed. Too many sources of error are detected where the brightness calibration does more harm than good. Instead, chromatic coordinates and smoothing of the time series are used for suppressing the diurnal and seasonal variations in scene illumination. (Less)
Please use this url to cite or link to this publication:
author
Forslund, Ludvig LU
supervisor
organization
course
NGEK01 20132
year
type
M2 - Bachelor Degree
subject
keywords
Physical Geography and Ecosystem Science, scene illumination, PhenoCam, Norunda, near-surface remote sensing, NDVI, digital images, Chromatic coordinates, clear-cut
publication/series
Student thesis series INES
report number
298
language
English
id
4286099
date added to LUP
2014-02-05 20:29:26
date last changed
2014-02-05 20:29:26
@misc{4286099,
  abstract     = {{Abstract
The use of inexpensive digital cameras in phenological research has been acclaimed since results in previous research have shown that they are reliable and precise in measuring greenness of vegetation. The work of this thesis aims to broaden the applicability by studying how well the method performs when measuring the regrowth of a clear-cut area. This is needed to complement existing research that primarily uses the technique to study phenology. Data acquisition from the digital images was carried out with the use of chromatic coordinates in comparison to parallel measurements of sensor-based NDVI. These time series were analyzed through correlations, measuring the linear dependency and covariance. The results show significant similarities between the two measured time series and the increase in vegetation denseness during the studied period (2011-2013). It is also shown that the chromatic coordinates are more sensitive to variations in chlorophyll greenness than NDVI. 
	These results, together with previous research, show that the digital camera is a valuable tool that is possible to apply to forest research and industry. Studies of clear-cut areas have shown that soil carbon release is strongly dependent on initial vegetation, a relationship that is possible to study following the results of this thesis. However, more research is needed to calibrate the method for measurements in different forest types and climate zones, before this is reality. The use of ground-level reference panels are also analyzed but fails to provide the reliable information needed. Too many sources of error are detected where the brightness calibration does more harm than good. Instead, chromatic coordinates and smoothing of the time series are used for suppressing the diurnal and seasonal variations in scene illumination.}},
  author       = {{Forslund, Ludvig}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{Student thesis series INES}},
  title        = {{Using digital repeat photography for monitoring the regrowth of a clear-cut area}},
  year         = {{2014}},
}