Geometric morphometrics is a powerful set of techniques that can be used to visualize and analyze the shape of artifacts. With the growing use of geometric morphometrics in archaeology, it is important to understand and identify limitations in the method. One such limitation is the accumulation of measurement error. Here, we investigate the impact of parallax or the effect of the position of an object in relation to the camera. We designed an experiment to assess the effect of parallax on measurements of artifact morphology by photographing a sample of artifacts at close range (50 cm) and systematically shifting the fixed angle of the camera relative to the artifact in five steps: 90°, 95°, 100°, 105°, and 110°. We took digital images of geometric microliths from three Jordanian Epipalaeolithic sites at each of the camera angles. We then digitized the outline of each artifact using 24 sliding landmarks. Our subsequent analyses of microlith shapes grouped by camera angle show that they are statistically indistinguishable from each other, which suggests that within these parameters, parallax has little effect on geometric morphometric measurements. While taking digital images directly above artifacts is ideal, the angle at which previously published photographs of artifacts is sometimes unknown. Our findings suggest that small deviations of the camera angle (up to 20° from horizontal) will not significantly impact geometric morphometric analyses.

中文翻译：

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评估视差在考古几何形态计量学分析中的作用

几何形态计量学是一组功能强大的技术，可用于可视化和分析工件的形状。随着几何形态计量学在考古学中的使用日益广泛，重要的是了解和识别该方法的局限性。这样的限制之一就是测量误差的累积。在这里，我们研究视差的影响或物体相对于相机的位置的影响。我们设计了一个实验，通过在近距离（50 cm）处拍摄伪影样本并通过五个步骤（90°，95°）系统地将相机的固定角度相对于伪影移动，来评估视差对伪影形态测量的影响。 ，100°，105°和110°。我们在每个相机角度拍摄了来自三个约旦上古石器时代遗址的几何微石的数字图像。然后，我们使用24个滑动地标数字化每个工件的轮廓。我们随后对按相机角度分组的微石形状的分析表明，它们在统计上是彼此无法区分的，这表明在这些参数内，视差对几何形态测量的影响很小。虽然在伪影上方直接拍摄数字图像是理想的，但先前发布的伪影照片的角度有时是未知的。我们的发现表明，摄像机角度的微小偏差（与水平方向的最大偏差为20°）不会显着影响几何形态分析。这表明在这些参数内，视差对几何形态测量的影响很小。虽然在伪影上方直接拍摄数字图像是理想的，但先前发布的伪影照片的角度有时是未知的。我们的发现表明，摄像机角度的微小偏差（与水平方向的最大偏差为20°）不会显着影响几何形态分析。这表明在这些参数内，视差对几何形态测量的影响很小。虽然在伪影上方直接拍摄数字图像是理想的，但先前发布的伪影照片的角度有时是未知的。我们的发现表明，摄像机角度的微小偏差（与水平方向的最大偏差为20°）不会显着影响几何形态分析。