A perceptual model of motion quality for rendering with adaptive refresh-rate and resolution

Limited GPU performance budgets and transmission bandwidths mean that real-time rendering often has to compromise on the spatial resolution or temporal resolution (refresh rate). A common practice is to keep either the resolution or the refresh rate constant and dynamically control the other variable. But this strategy is non-optimal when the velocity of displayed content varies. To find the best trade-off between the spatial resolution and refresh rate, we propose a perceptual visual model that predicts the quality of motion given an object velocity and predictability of motion. The model considers two motion artifacts to establish an overall quality score: non-smooth (juddery) motion, and blur. Blur is modeled as a combined effect of eye motion, finite refresh rate and display resolution. To fit the free parameters of the proposed visual model, we measured eye movement for predictable and unpredictable motion, and conducted psychophysical experiments to measure the quality of motion from 50 Hz to 165 Hz. We demonstrate the utility of the model with our on-the-fly motion-adaptive rendering algorithm that adjusts the refresh rate of a G-Sync-capable monitor based on a given rendering budget and observed object motion. Our psychophysical validation experiments demonstrate that the proposed algorithm performs better than constant-refresh-rate solutions, showing that motion-adaptive rendering is an attractive technique for driving variable-refresh-rate displays.</jats:p

Возможности флуоресцентной визуализации в оценке реваскуляризации гетеротопически трансплантированного сегмента трахеи приматов

Objective: to assess the potentials of using indocyanine green fluorescence angiography in evaluating revascularization of tissue-engineered construct that was obtained from the decellularized biological matrix of primate trachea, including using mesenchymal stem cells, after heterotopic tracheal allotransplantation. Material and methods. Tracheas were obtained from two male hamadryas baboons. After decellularization, 4 cm segments of tracheas were implanted under the lateral part of the latissimus dorsi in two healthy primates, one after recellularization with mesenchymal stem cells (animal 1), and the second without recellularization (animal 2). Immunosuppressive therapy was not performed. Blood flow in the transplanted segment of the trachea was evaluated 60 days after transplantation by surgical isolation of the flap of the latissimus dorsi with the transplanted segment of the trachea, while maintaining blood flow through the thoracodorsal artery. Indocyanine green near-infrared fluorescence angiography was visualized using a FLUM-808 multispectral fluorescence organoscope. Results. Sixty days after implantation, the tracheal cartilaginous framework macroscopically appeared to be intact in both animals, tightly integrated into the muscle tissue. The framework retained its natural color. After intravenous injection of indocyanine green, the tracheal vessels were visualized in both animals. Intercartilaginous vessels and portions of the cartilaginous semi-rings devoid of vessels were clearly distinguished. The entire implanted segment was almost uniformly vascularized. No local disruptions in blood supply were observed. The fluorescence brightness of the tracheal vessels was 193 ± 17 cu and 198 ± 10 cu in animals 1 and 2, respectively. The average muscle brightness in the implantation zone was 159 ± 9 cu and 116 ± 8 cu in animals 1 and 2, respectively. Conclusion. Indocyanine green fluorescence angiography is characterized by high-contrast images and high sensitivity. This facilitates vascular patency visualization and allows to assess the degree of neoangiogenesis after experimental transplantation of the tracheal segment, at different stages of experiment, without euthanizing the animal.Цель. Определение возможности использования индоцианиновой флуоресцентной ангиографии для оценки реваскуляризации тканеинженерной конструкции, полученной на основе децеллюляризированного биологического матрикса трахеи приматов, в том числе с использованием мезенхимных стволовых клеток, после ее гетеротопической аллотрансплантации. Материал и методы. Донорами трахеи послужили два самца павиана гамадрила. После децеллюляризации участки донорских трахей, по 4 см каждый, имплантированы под боковой участок широчайшей мышцы спины двум здоровым приматам, одному после рецеллюляризации мезенхимными стволовыми клетками (животное 1), второму – без проведения рецеллюляризации (животное 2). Иммуносупрессивную терапию не проводили. Наличие кровотока в трансплантированном сегменте трахеи оценивали через 60 суток после трансплантации путем хирургического выделения лоскута широчайшей мышцы спины с трансплантированным сегментом трахеи с сохранением кровотока по торакодорзальной артерии. Визуализацию инфракрасной индоцианиновой флуоресцентной ангиографии проводили с помощью мультиспектрального флуоресцентного органоскопа «FLUM-808». Результаты. Через 60 суток после имплантации хрящевой каркас трахеи макроскопически представлялся сохранным у обоих животных, плотно интегрированным в мышечную ткань, естественного цвета. После внутривенного введения индоцианина зеленого у обоих животных удалось визуализировать сосуды трахеи, четко различались межхрящевые сосуды и участки хрящевых полуколец, лишенные сосудов, весь имплантированный сегмент практически равномерно васкуляризирован, локальных нарушений кровоснабжения не отмечалось. Яркость флуоресценции сосудов трахеи у животного 1 составила 193 ± 17 у. е., у животного 2 – 198 ± 10 у. е., в то время как средняя яркость мышцы в зоне имплантации у животного 1 – 159 ± 9 у. е., а у животного 2 – 116 ± 8 у. е. Заключение. Индоцианиновая флуоресцентная ангиография характеризуется высокой контрастностью получаемых изображений, высокой чувствительностью, что может позволить визуализировать проходимость сосудистой сети и оценить степень неоангиогенеза после экспериментальной трансплантации сегмента трахеи на разных этапах эксперимента без эвтаназии животного

Fluorescence imaging in evaluating the revascularization of heterotopically transplanted primate trachea segment

Objective: to assess the potentials of using indocyanine green fluorescence angiography in evaluating revascularization of tissue-engineered construct that was obtained from the decellularized biological matrix of primate trachea, including using mesenchymal stem cells, after heterotopic tracheal allotransplantation. Material and methods. Tracheas were obtained from two male hamadryas baboons. After decellularization, 4 cm segments of tracheas were implanted under the lateral part of the latissimus dorsi in two healthy primates, one after recellularization with mesenchymal stem cells (animal 1), and the second without recellularization (animal 2). Immunosuppressive therapy was not performed. Blood flow in the transplanted segment of the trachea was evaluated 60 days after transplantation by surgical isolation of the flap of the latissimus dorsi with the transplanted segment of the trachea, while maintaining blood flow through the thoracodorsal artery. Indocyanine green near-infrared fluorescence angiography was visualized using a FLUM-808 multispectral fluorescence organoscope. Results. Sixty days after implantation, the tracheal cartilaginous framework macroscopically appeared to be intact in both animals, tightly integrated into the muscle tissue. The framework retained its natural color. After intravenous injection of indocyanine green, the tracheal vessels were visualized in both animals. Intercartilaginous vessels and portions of the cartilaginous semi-rings devoid of vessels were clearly distinguished. The entire implanted segment was almost uniformly vascularized. No local disruptions in blood supply were observed. The fluorescence brightness of the tracheal vessels was 193 ± 17 cu and 198 ± 10 cu in animals 1 and 2, respectively. The average muscle brightness in the implantation zone was 159 ± 9 cu and 116 ± 8 cu in animals 1 and 2, respectively. Conclusion. Indocyanine green fluorescence angiography is characterized by high-contrast images and high sensitivity. This facilitates vascular patency visualization and allows to assess the degree of neoangiogenesis after experimental transplantation of the tracheal segment, at different stages of experiment, without euthanizing the animal