@InProceedings{RosaNeAlStVaAl:2017:BiSaEs,
               author = "Rosa, Diogo Martins and Nelson, Bruce Walker and Almeida, Danilo 
                         Roberti Alves de and Stark, Scott Christopher and Valle, Dalton 
                         Freitas do and Almeida, Juliana Schietti de",
                title = "Bias and saturation in estimated LAD and LAI using a rangefinder 
                         ground LiDAR",
            booktitle = "Anais...",
                 year = "2017",
               editor = "Gherardi, Douglas Francisco Marcolino and Arag{\~a}o, Luiz 
                         Eduardo Oliveira e Cruz de",
                pages = "6117--6122",
         organization = "Simp{\'o}sio Brasileiro de Sensoriamento Remoto, 18. (SBSR)",
            publisher = "Instituto Nacional de Pesquisas Espaciais (INPE)",
              address = "S{\~a}o Jos{\'e} dos Campos",
             abstract = "Leaf area index (LAI) and canopy openness were estimated at 2m 
                         intervals along 900m of transect in each of four forest types 
                         comprising different parts of a topographic sequence in a Central 
                         Amazon terra firme forest. Both metrics were obtained with a 1000 
                         Hz rangefinder type LiDAR, using the distance to last return for 
                         each pulse. Pulses were directed vertically upward from the forest 
                         floor by an operator walking at constant speed. We avoided hours 
                         near noon, when direct sunlight could enter the detector. We 
                         estimated the leaf area density (LAD) of each voxel by the 
                         MacArthur-Horn method. We obtained LAI from the summed LADs of 
                         each voxel stack. Three causes of bias in LAD estimation are 
                         discussed. Histograms of LAI showed saturation, i.e. an upper 
                         limit of detectability, for all four forest types. Consequently, 
                         mean LAI did not differ between forest types, even if all 2m 
                         sections of transect were assumed independent (n=450). Corrections 
                         to these problems are being prepared, led by authors SCS and DRA. 
                         Canopy openness did differ between the four forest types. This 
                         suggests that LAI does differ but our unadjusted methods did not 
                         permit detection of this difference.",
  conference-location = "Santos",
      conference-year = "28-31 maio 2017",
                 isbn = "978-85-17-00088-1",
                label = "59530",
             language = "en",
         organisation = "Instituto Nacional de Pesquisas Espaciais (INPE)",
                  ibi = "8JMKD3MGP6W34M/3PSMCBF",
                  url = "http://urlib.net/ibi/8JMKD3MGP6W34M/3PSMCBF",
           targetfile = "59530.pdf",
                 type = "LIDAR: sensores e aplica{\c{c}}{\~o}es",
        urlaccessdate = "27 abr. 2024"
}