Fisheye Lens Research Articles

Contribution of Lasergrammetry, Photogrammetry and Electrical Tomography for the Survey and 3D Representation of Caves: Case Study of the Cave of Kef El Baroud, Province of Benslimane, Morocco

The modeling of caves is constantly evolving and the classic modeling tools are giving way to new techniques that are more precise and more practical, indeed scientists are increasingly using 3D modeling to improve the representations of caves, in this study we have used lasergrammetry and photogrammetry which occupy an increasing place in the 3D representation of caves. Their simplicity favors their use for recording and modeling the parietal morphology of caves and the detailed representation of the complexity of Endokarst. As part of the geomorphological study of the Kef El Baroud Cave which is located in the province of Benslimane in Morocco, two modeling methods were carried out, it is a digital survey by lasergrammetry and by photogrammetry of the cave. and its parietal morphologies. The study was completed by a topographical survey with a DistoX rangefinder. The geophysical contribution by electrical tomography was also carried out. The 3D terrestrial laser scanning technique was performed by a LEICA RTC 345 scanner. These measurements made it possible to reconstruct the evolutionary stages of the paragenetic morphologies, and their relationships with the local geomorphology, and the structural elements. The field measurements were integrated into the morphometric analyzes of the digital models, which allowed a large number of observations.The surveys also made it possible to compare the results with those of the photogrammetry carried out by a reflex camera and a wide-angle lens with appropriate editing software.Lasergrammetry and its application have enabled us to precisely position within the point cloud all the details of the covered wall, and thus constitutes, alongside photogrammetry, an interesting means for the geomorphological study of the Caves. An electrical tomography study was coupled with the other measurements and made it possible not only to delimit the walls of the Cave according to the resistivity gradients but also to detect the very probable presence of fractured zones under the Cave which could constitute an aquifer.

Study on the Correlation Analysis between Urban Morphological Factors and Microclimate Based on Empirical Methods on a University Campus in a Hot-Summer–Cold-Winter Region

With the continuous progress of urbanization, contemporary scholars are increasingly focusing their attention on the study of urban microclimates. This research aims to investigate the relationship between urban morphology and microclimates in regions characterized by hot summers and cold winters. Environmental meteorological data, including temperature, solar radiation, and wind speed during the spring and summer seasons, were collected through on-site monitoring in a specific area of Shanghai. Various methods, such as on-site surveys and drone photography, were employed to obtain and analyze a range of urban morphological parameters, including floor area ratio (FAR) and greenery ratio (GnPR). The sky view factor (SVF) was determined using a fisheye lens technique. Subsequently, the collected datasets were analyzed to assess the varying impact of distinct urban morphological factors on microclimates. The findings indicate a significant correlation between different building morphology factors and temperature and solar radiation during spring, while their associations with wind speed become more prominent in summer. Notably, greenery and pavement demonstrate stronger correlations with temperature and radiation in summer, aligning with the seasonal growth patterns of plants. These research findings provide both a theoretical foundation and practical guidelines for the urban design of environmental microclimates.

Fisheye lens-based UWOC system with an FOV of ±90°.

The link alignment is a challenge in underwater wireless optical communication (UWOC). This paper proposes a UWOC system adopting a fisheye lens with a field of view (FOV) of ±90° at the receiver to alleviate alignment requirement, and a mobile scanning device (MSD) is exploited to track the variation of the imaging position generated by the fisheye lens due to different incidence angles. In a 7-m tap water channel, a transmission with a data rate of 400 Mbps and an FOV of ±90° is realized with 16-quadrature amplitude modulating-orthogonal frequency division multiplexing (16-QAM-OFDM) modulation and orthogonal matching pursuit (OMP) channel estimation algorithm.

A compact wide-angle DUV lens suitable for SO2 monitoring

We report the design and development of a compact wide-angle deep ultraviolet (DUV) lens suitable for sulfur dioxide (SO2) monitoring. The lens (focal length = 10 mm, F-number = 4, full field of view = 35°) is made of synthetic quartz (SiO2, SQ) glass, sapphire (Al2O3) crystal, and calcium fluoride (CaF2) crystal whose dimensions are optimized for 290–320 nm wavelengths. Compared to a conventional doublet lens with the same focal length, F-number, and full field of view, our design exhibits slight vignetting and peripheral astigmatism but with corrected chromatic aberrations, smaller focal shifts (127 µm), tighter spot sizes (19–24 µm), and better image resolution and contrast (modulation transfer function, MTF ≥ 0.4). The lens properties have also been confirmed experimentally with the fabrication and evaluation of an actual lens based on our design. The actual lens exhibits a barrel-type distortion of 3.3 %, relative illumination of 94–100 % at 0–5° field angles, and a tangential MTF performance curve similar to what are expected from the design. Our compact lens is shown to exhibit better properties than conventional lenses and promises better performance in wide-angle DUV imaging applications, especially for SO2 detection.

Actual sky visibility under shading by trees with different crown densities

Introduction. The development of green infrastructure is an important task in urban planning strategies to reduce urban heat island effect and improve urban ecosystem. The aim of this study is to determine the actual visibility of the skyline when shaded by trees of different crown densities. The scientific novelty is that for the first time a study of the actual sky visibility with trees shading as complex heterogeneous systems has been conducted to assess the effect of mitigating of urban heat island. The practical significance lies in the establishment of the actual visibility of the firmament under the shading of trees with different crown density, which enables the correction of simulation models to analyze the parameters of the microclimate of the urban environment under given climatic conditions.
 
 Materials and methods. Various approaches to determining the sky visibility are considered. Direct measurements were made by photographing with a special fisheye lens and a smartphone. The research was carried out in a temperate continental climate (according to the international climate classification Köppen — type Dfa). Several tree species most commonly found in landscaping under the climate conditions in question and having different crown densities were selected: elm, oak, maple and poplar. For each, several samples were selected as required for data averaging. A total of 27 samples were studied.
 
 Results. A diagram of measured averaged values of the sky visibility factor was plotted, taking into account shading by trees with different crown densities in different periods of the year. To protect trees with dense spreading crowns from the direct solar radiation in the summer daytime, it is better to use trees with dense spreading crowns to intensify the radiant heat exchange of the urban surface with the sky at night — trees with less dense crowns. In case of the need to soften the urban heat island during the day, hybrid solutions are the most effective.
 
 Conclusions. The actual assessment of the sky visibility, made by the authors taking into account shading by trees, allows us to make corrections in simulation models to analyze the parameters of the microclimate of the urban environment under the given climatic conditions. The results of the study make it possible to select the type of tree providing the required shading and urban heat island’s mitigation effect.

Development of an Injection Mold with High Energy Efficiency of Vulcanization for Liquid Silicone Rubber Injection Molding of the Fisheye Optical Lens

Liquid silicone rubber (LSR) techniques are experiencing exponential growth, particularly in the field of high technology due to the low-temperature flexibility, superior heat stability, chemical resistance, and aging resistance of LSR components. Enhancing the curing rate of LSR parts in liquid silicone rubber injection molding is an important research topic. In this study, an injection mold with high energy efficiency of vulcanization for the liquid silicone rubber injection molding of a fisheye lens was developed and implemented. The LSR injection mold has a conformal heating channel (CHC) and conformal cooling channel (CCC) simultaneously. The function of CHC is to enhance the curing rate of a fisheye lens in the LSR injection molding to meet the requirements of sustainable manufacturing. The curing rates of a fisheye lens were numerically examined using the Moldex3D molding simulation software. It was found that the curing rate of the fisheye optical lens cured by injection mold with CHC was better than that of the injection mold with a conventional heating channel. The curing efficiency could be increased by about 19.12% when the heating oil temperature of 180 °C was used to cure the fisheye optical lens. The simulation results showed that the equation y = −0.0026x3 + 1.3483x2 − 232.11x + 13,770 was the most suitable equation for predicting the curing time (y) through the heating oil temperature (x). It was found that the trend of the experimental results was consistent with the simulation results. In addition, the equation y = −0.0656x2 + 1.5827x − 0.894 with the correlation coefficient of 0.9974 was the most suitable equation for predicting the volumetric shrinkage of the fisheye optical lens (y) through the heating oil temperature (x). The volume shrinkage of the fisheye optical lens cured by injection mold with CHC was very similar to that of the injection mold with a conventional heating channel. The maximum volume shrinkage of the fisheye optical lens cured at 180 °C was about 8.5%.

A Theory of Change for Artistic Activism

Abstract Artistic activism intervenes in, and through, culture to animate ideas with emotions—charge them with affect—to motivate action, and change material conditions. Artistic activism also animates lived experience through emotions and, through its representation, gives rise to ideas and ideals. Yet we have no theory of change for how this might work. This article provides a model to think through and reflect upon “artistic activism,” or whatever name it goes by, as a complex practice that combines the affective power of the arts with the effective aims of activism. This gives us a wide-angle lens with which to see how artistic activism might create change. The model is then applied to a real-world creative activism example: the Undocubus, an intervention by young undocumented immigrants in the southern United States. The model’s macro view aids with thinking through and assessing more specific and necessarily contextual micro theories of change that are applied, consciously or unconsciously, by artistic activists and those they work with. The applied micro-view tests out its alignment with an example of practice. Most importantly, a comprehensive theory of change for artistic activism can provide clarity and direction as to where to intervene to maximize change.

Species independence of eye lens dimensions in teleosts and elasmobranchs.

The vertebrate eye lens grows incrementally, adding layers of elongated, tightly packed lens fiber cells at the outer margin of the lens. With subsequent growth, previously-deposited fiber cells degrade, leaving a region of fully denucleated and organelle-free cells which are responsible for the high transparency and low light scattering characteristics of the lens. The objective of this study was to determine if the horizon separating the gelatinous outer cortex of the lens from its hardened interior occurred at a consistent location within the lens of several teleost and elasmobranch fish species, and could be linked to fiber cell morphology or function. A fixed ratio of 0.69±0.01 of hardened eye lens diameter (HD) to overall eye lens diameter (LD) was observed in a broad size range of Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), thorny skate (Amblyraja radiata) and round ray (Rajella fyllae). The location of the hardened lens horizon was similar to that reported for optical plasticity and spherical aberration, but not that of fiber cell denucleation, suggesting that fiber cell dehydration continues after the loss of internal organelles. Our findings support a previous suggestion that the maintenance of optical quality during fish eye lens growth requires a precisely-fixed HD:LD ratio, while the ubiquity of a fixed ratio across fish taxa may suggest that many fish species possess a common refractive index profile. The linear relationship between HD and fish length should allow fish length to be backcalculated from the diameter of the isolated lens core, thus aiding research using isotope ratios of lens laminae or inner cores to reconstruct early life history events.

Impacts of canopy structure on the sub-canopy solar radiation under a deciduous forest based on fisheye photographs

Forest canopy in a deciduous forest has significant sheltering effects on the sub-canopy solar radiation, significantly influencing the energy balance of snow and permafrost beneath the forest and their spatial distribution. This study employs a digital camera mounted with a fisheye lens to acquire photographs at various times in a growth cycle of the forest canopy at three selected sites in a deciduous forest near the Greater Khingan Mountains Forest Ecological Station, Northeast China. The vegetation types and conditions at the selected sites include P1 in Ledum-Claopodium-L. dahurica, P2 in Carex tato-L. dahurica, and P3 in Betula fruticosa-L. dahurica. After necessary image processing, these photographs were used to identify the canopy structure and its impacts on the sub-canopy solar radiation. Results show that fisheye photographs can successfully capture the forest canopy structure and are useful in estimating the sub-canopy solar radiation. The order of sheltering effects from the largest to the smallest on sub-canopy solar radiation at three selected sites is P3, P1, and P2, highly depending on the canopy density. Then sub-canopy solar radiation was calculated using fisheye photographs and an algorithm validated by in-situ observed solar radiation beneath the canopy at P1 and P3. The results are reasonable, although the accuracy seems compromised due to the mismatch of conditions for calculation and observation. Results also show that the mean annual solar radiation above the canopy was about 148.3 W/m2 in 2018, and the mean annual solar radiation values beneath the canopy were about 90.0, 123.8, and 61.0 W/m2 at P1, P2, and P3, with only 60%, 84%, and 42% of the total solar radiation penetrating through the canopy, respectively. Even in winter, when the trees are leafless, the canopy sheltering effects cannot be ignored in dense forests. Despite the limitations, fisheye photographs and related algorithms are useful in investigating the forest canopy structure and its impacts on sub-canopy solar radiation.

Continuous Vat Photopolymerization for Optical Lens Fabrication

Optical lenses require feature resolution and surface roughness that are beyond most (3D) printing methods. A new continuous projection-based vat photopolymerization process is reported that can directly shape polymer materials into optical lenses with microscale dimensional accuracy (< 14.7µm) and nanoscale surface roughness (< 20nm) without post-processing. The main idea is to utilize frustum layer stacking, instead of the conventional 2.5D layer stacking, to eliminate staircase aliasing. A continuous change of mask images is achieved using a zooming-focused projection system to generate the desired frustum layer stacking with controlled slant angles. The dynamic control of image size, objective and imaging distances, and light intensity involved in the zooming-focused continuous vat photopolymerization are systematically investigated. The experimental results reveal the effectiveness of the proposed process. The 3D-printed optical lenses with various designs, including parabolic lenses, fisheye lenses, and a laser beam expander, are fabricated with a surface roughness of 3.4nm without post-processing. The dimensional accuracy and optical performance of the 3D-printed compound parabolic concentrators and fisheye lenses within a few millimeters are investiagted. These results highlight the rapid and precise nature of this novel manufacturing process, demonstrating a promising avenue for future optical component and device fabrication.

COMPARISON OF TWO MATHEMATICAL MODELS FOR FISHEYE CAMERAS APPLIED IN THE ORB-SLAM

Abstract. Fisheye lens cameras are becoming increasingly popular for vSLAM applications due to their wide field of view (FoV), providing more features to be tracked in a single image shot. However, the complex lens geometry involved in the image formation process still limits their full potential, especially when points in the hyperhemispherical field are unmodeled. In this paper, we compare two adaptations of ORB-SLAM for fisheye lens cameras, considering the use of the rigorous projection model (equisolid-angle) versus the use of the generic projection model (EUCM). The ORB-SLAM versions were adapted for real-time processing on the Nvidia Jetson TX2 board. The experiment was conducted using hyperhemispherical images obtained with a Ricoh Theta S camera. Our results showed that the trajectory estimated with the equisolid-angle ORB-SLAM had smaller discrepancies, compared to the reference trajectory, than the EUCM ORB-SLAM. This suggests that a rigorous photogrammetric model with a suitable treatment of hyperhemispherical points is beneficial for trajectory estimation.

EFFECTS OF HYPER HEMISPHERICAL FIELD IN BUNDLE ADJUSTMENT WITH FISHEYE IMAGES

Abstract. The large field of view and compact structure make fisheye lens cameras an attractive technology for mobile mapping systems and visual navigation. Fisheye cameras usually have a field of view equal to or higher than 180°. Lenses that can capture light rays coming from angles larger than 180° are known as hyper hemispherical lenses. Some of the existing mathematical models can be unsuitable for those points beyond the 180° field of view when performing photogrammetric processes based on these equations, underexploring the full potential of fisheye lens cameras. In this case, depending on the selected projection model, points appearing in the hyper hemispherical (HH) field can produce blunders in the bundle adjustment. Nevertheless, most of the available solutions for camera calibration and bundle adjustment were implemented using the equidistant model. Therefore, the points located in the hyper hemispherical field are often removed from the bundle adjustment either during keypoint detection or by applying a mask to remove the entire HH field from the images. In this paper, we assessed experimentally the hypothesis that using the original HH full-field image introduces blunders, deteriorating the bundle adjustment. The experiments were performed with a Ricoh Theta S 360° camera which was mounted on a backpack platform. The camera was set in video mode, and frames were captured at a rate of 1 fps, while traversing an urban street, generating 307 frames. Experiments were performed, including or removing HH points in the bundle adjustment. The results show that the errors in the dataset with the hyper hemispherical field were larger than the ones using cropped images.

Role played by port drains in a Maxwell fish-eye lens

The Maxwell fish-eye lens was proposed to reach super-resolution with the addition of a wave drain, and the interaction of multiple drains is theoretically predicted to improve subwavelength resolution further. In this paper, we discuss the role played by port drains in optical absolute instruments and verify by wave simulation that the coupling nature for the wave source and drain applies correctly in the picture of scanning imaging for an absolute instrument. This work has prospects for scanning near fields shaped from far-field wave propagation.

Possible approaches for processing of spherical images using SfM

Spherical cameras are being used more frequently in surveying because of their low cost and possibility to process spherical images with conventional SfM methods. Fish-eye lenses are now frequently found on modern 360° cameras, allowing for the capture of the entire scene and subsequent model reconstitution by a non-photogrammetrist specialist. Gyrospherics are a feature of cameras that ensure image stabilization to reduce blur when the camera is moving. This feature allows it to capture moving scenes in time-lapse mode. However, two main factors - hardware parameters and software algorithms - affect the quality of the images that are captured. The 360° camera design allows for a variety of data processing methods by SfM. These images were created using multiple image sensors and lenses from each 360° camera. These images can be processed individually or by applying rules to define relationships between images. Also, images from cameras can be stitched and processed with a spherical camera model. In this paper is proposed processing methods of data from 360° cameras and estimated accuracy of each method.

Bridge Deformation Measurement Using Unmanned Aerial Dual Camera and Learning-Based Tracking Method

Bridge deformation response data are the basis for calculating the dynamic parameters of the bridge, and it is of great significance to accurately measure the deformation response of the bridge during the load test and service conditions. A bridge deformation measurement method using an unmanned aerial system (UAS) with dual cameras and a deep learning-based object tracking method is proposed to measure the bridge deformation. The contributions are as follows: (1) To address the problem that the movement of the UAS brings error to the deformation measurement results, dual cameras with telephoto and wide-angle lenses are used to simultaneously capture the deformed points and stable points on the bridge, so as to simultaneously measure the deformation of the bridge and the displacement of the UAS, and then the displacement of UAS is eliminated by using the homography relationship between the two cameras. (2) To solve the problem that the traditional digital image correlation-based displacement measurement method is easily disturbed by factors such as light changes and occlusion, a displacement calculation method based on object detection network and target tracking algorithm is proposed to achieve the stable target displacement measurement. Finally, the proposed method was verified in a laboratory test and applied to the deformation measurement of an in-service bridge to verify the practicability of the proposed method.

Compact 2D electron analyzer CoDELMA: Simultaneous wide reciprocal and real space analysis using wide-angle deceleration lens, CMA and projection lens

A compact wide-acceptance angle (around ± 50°) high-energy-resolution 2D electron analyzer CoDELMA (Compact DELMA) is proposed, constructed and tested. CoDELMA is composed of a recently-proposed variable-deceleration-ratio wide-acceptance-angle electrostatic lens (VD-WAAEL), a cylindrical mirror analyzer (CMA) and a projection lens. After a brief review of VD-WAAEL, the use of a plane grid in the lens is presented as a new design option, which allows keeping the focusing angle almost constant irrespective of the deceleration ratio. A detailed consideration is given to the combination of CMA and a projection lens, which allows simultaneous analysis of wide reciprocal ( ± 8°) and real space ( ± 5 mm) at the entrance of CMA. CoDELMA is the successor to the previously developed DELMA instrument including a concentric hemispherical analyzer. The whole system of CoDELMA becomes much more compact than that of DELMA owing to the use of VD-WAAEL and CMA, and this results in considerable reduction of the production cost. Results of test measurement of energy spectrum and angular distribution using an electron gun as an excitation source confirmed that the energy resolution and the acceptance angle are almost the same as the designed values.

Analogy of the interior Schwarzschild metric from transformation optics.

In this paper, we make an analogy of the interior Schwarzschild metric from transformation optics (we call the method transformation cosmology). It is shown that a simple refractive index profile is sufficient to capture the behavior of the metric to bend light. There is a critical value of the ratio of the radius of the massive star to the Schwarzschild radius, which is exactly related to the condition of collapsing into a black hole. We demonstrate the light bending effect for three cases from numerical simulations as well. Especially, we find that a point source at the photon sphere will form an image inside the star approximately, and the equivalent lens is like Maxwell's fish-eye lens. This work will help us to explore the phenomena of massive stars with laboratory optical tools.

Reconstructions of individual fish trophic geographies using isotopic analysis of eye-lens amino acids.

Fish eye lenses are a proteinaceous structure that grows by accumulating layers in a chronological manner. Each layer becomes metabolically inert, capturing the ratio of heavy/light carbon and nitrogen isotopes at time of formation. Therefore, eye lenses contain chronological isotopic records and can be used to create a temporal isotopic history throughout an individual's lifetime. We analyzed eye lens amino-acid δ15N to address spatio-temporal baseline variability and to reconstruct trophic histories of 10 individual Red Snapper. Proteins from sequential eye lens laminae were derivatized to measure 10 amino acids, from which glutamic acid (trophic) and phenylalanine (source) were used to estimate trophic positions at different points in life. Best-fitting regressions were generated to represent individual (R2 ≥ 0.89) and generalized (R2 = 0.77) trophic trajectory for Red Snapper. The resulting trophic trajectories indicated an increase in trophic position with increasing length. Until recently, there has not been a lifetime isotopic structure with enough organic nitrogen to recreate geographic histories using compound-specific stable isotope analysis of amino acids (CSIA-AA). This study confirms that eye-lens laminae can be used to reconstruct trophogeographic histories via CSIA-AA.

Optimization of Lai Estimation Method Based on Smartphones with Fisheye Lens

Leaf area index (LAI) is an important biological factor reflecting vegetation growth and forest ecosystem. LAI can be used to obtain plant health status, carbon cycle, and surrounding ecological environment effectively. In this study, the smartphone was equipped with a fisheye lens, and the optimization method was used to estimate LAI, which was compared with digital hemispherical photography (DHP) to investigate the possibility of the new method for LAI estimation. The hemispherical image was divided into blocks, and the optimized Otsu method was used for algorithm segmentation, which can effectively distinguish vegetation from the sky. Concurrently, when the gap fraction inversion LAI was performed, the linear inversion algorithm was improved based on single-angle inversion, and the LAI was obtained by inversion through the linear fitting of the mul-tiangle gap fraction. The experimental sample was located in Olympic National Forest Park in Beijing. Three coniferous mixed forests and three broadleaved forests were selected from the experimental sample. LAI measurements from smartphones were compared with those from DHP. In the samples for mixed coniferous forests, the values for coefficients of determination R^2 were 0.835, 0.802, and 0.809, and root mean square errors (REMS) were 0.137, 0.120, and 0.147. For the broadleaf forest samples, the values for R² were 0.629, 0.679, and 0.758, and REMS were 0.144, 0.135, and 0.137. The R^2 and RMES for the overall data was 0.810 and 0.134, respectively, and a good agreement between the LAI measurements from the proposed method and those from the DHP supports an accurate estimation. The results show that the use of a fisheye lens on a smartphone can effectively and accurately obtain tree canopy LAI. This provides a fast and effective new method to measure LAI of forest vegetation near the ground, which is of great significance for studying the interaction between plant growth status, ecological environment, and phenological changes.

Sacred Sounds, Secular Spaces: Transforming Catholicism Through the Music of Third Republic Paris by Jennifer Walker (review)

Reviewed by: Sacred Sounds, Secular Spaces: Transforming Catholicism Through the Music of Third Republic Paris by Jennifer Walker Joseph F. Byrnes Sacred Sounds, Secular Spaces: Transforming Catholicism Through the Music of Third Republic Paris. By Jennifer Walker. (New York: Oxford University Press. 2021. Pp. x, 355. $74.00. ISBN 978-0-19-757805-6.) Paris was the setting for compositions and performances of religious (and here read Catholic) music in secular venues. Jennifer Walker offers as her first example a performance of the mystery play Sainte-Genviève de Paris in the Montmartre cabaret Le Chat Noir on January 6, 1893. For Walker, the history of such performances is, in effect, a history of Church-State interchange, yea even reconciliation. She narrates the rich and varied musical history of a secularized Catholicism, which presumably gives the lie to the old standard notion of "two Frances"—a Church and State in mutual opposition. Musical notation is integral to the analysis of religious music throughout the book, which is a volume in a remarkable series of studies labelled "AMS Studies in Music," a joint effort of the American Musicological Society and the Oxford University Press. Footnotes include a wide and detailed range of references, with the French texts translated by the author expanded to include preceding and following sentences. Too extensive to be read in full—they almost created an overweight metanarrative—these notes can serve for subsequent use by researchers. In "The Catholic Church in Republican Musical Aesthetics," Walker introduces both the Catholic in-house churchmen and musicologists who tried to define "sacred" music and the secular critics who, surprisingly, even more severely limited the texts, melodies, and harmonies that deserved the label of "sacred music." At the center of such discussions figured the works of Dubois, Fauré, Massenet, Saint-Saëns, and Widor. The centerpiece of the next chapter, "Pious Puppets and the Limits of Symbolism," is the puppetry of the Petit-Théâtre de la Marionnette, wherein the musical narratives were almost exclusively Catholic, to wit, Tobie (Tobias) and Noël, ou le Mystère de la nativité. Reporters and critics provided detailed presentations of story and musical line. In "Sincerity and the Limits of Symbolism," the author juxtaposes the Petit-Théâtre's offering of La Légende de Sainte-Cécile to [End Page 415] the Théâtre de Vaudeville's Les Drames sacrés to show again how critics, believers, and non-believers alike demanded text fidelity and musical seriousness. In chapters four and five, Walker trains a much more wide-angle lens on the series of concerts at the Church of Sainte-Eustache, "The Republic's Sacred Cathedral," and at the Trocadéro, "The Republic's Secular Cathedral." The Sainte-Eustache oratorio performances were religious in musical content but were problematically tied to the government's control of the 1900 Exposition Universelle. Handel's Messiah, Berlioz's Requiem, Gounod's Mors et Vita, Wagner's La Cène des Apôtres, Massenet`s La Terre promise, and Bach's Saint Matthew Passion constituted the series, the use of Sainte-Eustache as a "theater" disturbing Cardinal François Richard and pleasing secular critics. Walker calls the ensemble a "Repertoire for the Republic." She details here the subtleties of the story lines, the mechanics of the musical lines, their place within each composer's total oeuvre, and the usually favorable critical response, concluding, "Much to the Church's chagrin, the church of Saint-Eustache thus became a key site in dismantling the polarizing dichotomy between Church and State" (p. 191). At the Trocadéro and the Champ de Mars, the 1900 Exposition Universelle featured displays of Catholic art, literature, and music. Cardinal Richard was absent from the opening liturgical celebration, but in his place Father Stéphen Coubé preached reconciliation with the Republic, pointing out that work, science, and art could be sanctified and given moral force by the Church. For all this to take place in 1900, ideologies had shifted in the preceding ten years, according to Walker, although, in fact, featured composers and works in 1889 (the Fair commemorating the 1789 Revolution) and 1900 overlapped considerably in their story, musical lines, and critics' responses. Brand...