For local intensity-based image registration methods, a template of a predefined size is adopted. Some measure of similarity between the images is used to determine when the optimal alignment has occurred. Most intensity-based similarity utilizes the statistical and spatial information of an image. However, there are significant nonlinear radiometric differences between infrared and visible data. Images of natural scenes usually do not have enough spatial features within the template. Hence, many similarities will be useless when dealing with infrared and visible data. Minor eigenvalues (ME) image registration similarity is presented with the exploitation the spectral properties of remote sensing images. ME similarity is based on the linear spectral mixture model and detects control points through searching the minimum of ME of the covariance matrix. Experiments on Landsat-7 satellite Enhanced Thematic Mapper Plus data are performed to verify and evaluate the effectiveness. Transformation performance curves, correct match ratio (CMR), and registration accuracy are also discussed. According to the data, root-mean-square error of phase correlations is 0.0722 pixels and the CMR of ME similarity is nearly 100%. The results on the basis of TM1, TM2, TM3, and TM4 band images indicate that the proposed similarity holds promise for infrared and color image registration in natural scenes, with advantages over previous normal mutual information and gradient mutual information similarities.
For multispectral imagery, spatial registration between bands is a very important part of the overall quality of the
multispectral imagery product. Due to the significant differences in scene reflectance at different wavelengths, mostly
multispectral imagery registration methods are unreliable. In this paper, a robust multispectral imagery registration
method is presented. As we know, the spectral information (endmembers) of some pixels will been confused when
multispectral imagery is mis-registered. The change of confused endmembers can be estimated through observing minor
eigenvalues. Based on this property, a minor and noise component criterion is defined. The best alignment is reached
when their minor and noise component is at its minimum. Experiments were conducted using multispectral imagery from
the ETM Satellite. And corresponding registration performance curve is given. Multispectral imagery is pre-registered
with the method of normalized mutual information. Computer simulations show that the normalized mutual information
method may have a deviation about 10 pixels between a pair of images. The method we presented can have a deviation
less than 1/4 pixel. Registering curve show that this method is efficient and robust, it can be used for precise
multispectral imagery registration.
A novel phase demodulation and projector design method for 3D profile measuring is presented. The system employs a LD as a light source and CCD as a detector. LD and small optical fiber space encoding projector is used to make the system tight and convenient. The light is guided into optical fiber by optical fiber coupler. This method is based on two-optical-fiber interference principle. The projector is made up by six single-mode fibers. Six single-mode fibers are ranged closely into right line to form three pairs of coherent light sources. The space length of every pair of optical fibers is different. The ratio of space length is 1:3:5. Three frames of deformed interference pattern with different spatial frequency are produced. The phase can be demodulated through algebraic operation, arc cosine and phase unwrapping of three frames of interferogram. Theoretical model is established for optical 3D measurement. Phase formula and unwrapping method is given. Numerical simulation and experiment results show that this way is feasible.
Under considering energy transfer up-conversion (ETU) and ground state re-absorption (GSA), the rate equations of the Tm,Ho:YLF laser are given. The influence of ETU on fractional thermal loading is calculated for the continuous wave and Q-switched Tm,Ho:YLF lasers and the results show that the fractional thermal loading critically depends on the pump-to-mode size ratio. Furthermore, the fractional thermal loading depends on the pulse repetition frequency for a Q-switched laser. The temperature distributions of a Tm,Ho:YLF crystal under different pump powers have been analyzed. The thermal focal length as a function of pump power is calculated.
The influence of energy-transfer up-conversion (ETU) on diode-end-pumped actively Q-switched Tm,Ho:YLF lasers is
investigated by the rate equation analysis. The theoretical results show that the energy-transfer up-conversion reduces not
only pulse energy but also effective upper level life. The practical example of the diode-end-pumped Q-switched
Tm,Ho:YLF laser has been used to verify the present model.
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