- Lunar Clinopyroxene Abundance Retrieved from M3 Data Based on Topographic Correction

The full potentiality of spectral vegetation indices (VIs) can only be evaluated after removing topographic, atmospheric and soil background effects from radiometric data. Concerning the former effect, the topographic effect was barely investigated in the context of VIs, despite the current availability correction methods and Digital elevation Model (DEM). In this study, we performed topographic correction on Landsat 5 TM spectral bands and evaluated the topographic effect on four VIs: NDVI, RVI, EVI and SAVI. The evaluation was based on analyses of mean and standard deviation of VIs and TM band 4 (near-infrared), and on linear regression analyses between these variables and the cosine of the solar incidence angle on terrain surface (cos i). The results indicated that VIs are less sensitive to topographic effect than the uncorrected spectral band. Among VIs, NDVI and RVI were less sensitive to topographic effect than EVI and SAVI. All VIs showed to be fully independent of topographic effect only after correction. It can be concluded that the topographic correction is required for a consistent reduction of the topographic effect on the VIs from rugged terrain.

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Aspects of atmospheric and topographic correction of high spatial resolution imagery

2012 IEEE International Geoscience and Remote Sensing Symposium ◽

10.1109/igarss.2012.6351719 ◽

2012 ◽

Cited By ~ 1

Author(s):

Daniel Schlapfer ◽

Rudolf Richter ◽

Tobias Kellenberger

Keyword(s):

Spatial Resolution ◽

High Spatial Resolution ◽

Topographic Correction ◽

High Spatial Resolution Imagery

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Topographic Correction for the Data of SQUID-based TEM Using a Ground Loop

Journal of Environmental and Engineering Geophysics ◽

10.2113/jeeg24.1.111 ◽

2019 ◽

Vol 24 (1) ◽

pp. 111-117

Author(s):

Yanju Ji ◽

Yi Zhao ◽

Shangyu Du ◽

Dongsheng Li ◽

Yi Zhang ◽

...

Keyword(s):

Magnetic Field ◽

Quantum Interference ◽

Low Frequency ◽

High Sensitivity ◽

Absolute Error ◽

Correction Method ◽

Topographic Effects ◽

Topographic Correction ◽

Transient Electromagnetic ◽

Ground Loop

Superconducting quantum interference device (SQUID) can be used to detect the signal of transient electromagnetic method (TEM) due to its superiority of high sensitivity in the low frequency range. However, the measuring direction of SQUID is hardly consistent with the normal direction of the transmitting coil of a TEM system because of the undulating topography in the field. In this case, the central magnetic field measured by SQUID is only a component of the theoretical central magnetic field. There will be larger errors if we directly use the measured central magnetic field for geological interpretation. To solve this problem, we propose a topographic correction method for the data of SQUID-based TEM using ground loop. The theoretical central magnetic field of the ground loop is calculated after the trapezoidal transmitting current wave is turned off. Then, we use the theoretical central magnetic field of the ground loop as the reference to correct the measured central magnetic field of SQUID-based on the trigonometric function relation between the measuring direction of SQUID and the topographic inclination. The experiment of SQUID-based TEM using a ground loop was carried out in the field. The result shows that at the measurement point with larger topographic inclination, the average absolute error of the measured central magnetic field reduces significantly with the proposed correction method. This method can also be applied to the correction of complex topographic effects when using SQUID to measure three components of magnetic field.

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