author = "Torre{\~a}o, Jos{\'e} R. A.",
                title = "Shape from shading and intensity gradient",
                 year = "2000",
               editor = "Carvalho, Paulo Cezar Pinto and Walter, Marcelo",
         organization = "Brazilian Symposium on Computer Graphics and Image Processing, 13. 
            publisher = "IEEE Computer Society",
              address = "Los Alamitos",
                 note = "The conference was held in Gramado, RS, Brazil, from October 17 to 
             keywords = "computer vision, shape from shading, intensity gradient, shape 
                         estimation, brightness gradient, Green function approach, 
                         shape-from-shading, GSFS, single brightness image, uniform 
                         disparity field, matching image, linear expansion, reflectance 
                         map, surface gradient, closed-form depth map, free parameters, 
                         parameter estimation, depth estimate, higher-frequency components, 
                         imaged surface, real images, computer vision technique.",
             abstract = "We present a novel algorithm for shape estimation, using both 
                         brightness and brightness gradient as input data. Our algorithm is 
                         an improvement of the recently introduced Green's function 
                         approach to shape-from-shading (GSFS). In GSFS, we assume that the 
                         single brightness image will be matched to a second image through 
                         a uniform disparity field, and solve for the matching image via 
                         Green's function. When a linear expansion of the reflectance map 
                         is considered, the matching image can be related to surface 
                         gradient, leading to a closed-form depth map whose free parameters 
                         are easily estimated. The author shows that the same procedure can 
                         be repeated with the gradient image as input; a second depth 
                         estimate thus results which takes into account higher-frequency 
                         components of the imaged surface. Extensive experimentation with 
                         synthetic and real images corroborates the advantage of the new 
  conference-location = "Gramado, RS, Brazil",
      conference-year = "October",
         organisation = "SBC - Brazilian Computer Society",
           targetfile = "7-14.pdf",
        urlaccessdate = "2020, Nov. 29"