UAVs for aerial photography have been promoted as the new way to map large areas efficiently. The cost of the technology is comparable to that of GNSS survey, and the results are comparable with much greater resolution. This is a major leap forward. The objective of this paper is to analyze the survey methodologies using a Lidar- and UAV-based photogrammetry and compare an overall approach over a chimney study. The whole analysis is done for a chimney under construction at Qasimpur, Harduaganj in Aligarh district in the Indian state of Uttar Pradesh. Chimney is one of the prominent structures in any thermal power plant, and its stability is really an issue for which conventionally total station and other instruments were used. The primary function of chimney is to discharge pollutants into atmosphere at such heights and velocities that the concentration of pollutants deemed harmful to the environment is kept within acceptable limits at ground level. Due to the development in unmanned aerial systems, survey has become quite accurate and accessible. Nowadays, it has been possible to study the structure more in detail and critical analysis can also be done using the point cloud data of the structure. Creation of mesh surface using these point cloud can be used to identify the undulation and defects in structure. In this paper, both UAV images and Lidar data are used to analyze the same structure from two different perspectives. Computing eccentricity of the structure using these two methodologies is further compared for accuracy, and an effort is made to understand the practicality of both survey methods.

中文翻译：

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使用无人机图像和激光雷达进行烟囱研究的调查方法分析

用于航拍的无人机已被推广为有效绘制大面积地图的新方法。该技术的成本可与 GNSS 调查相媲美，结果具有可比性，分辨率更高。这是一个重大的飞跃。本文的目的是使用基于激光雷达和无人机的摄影测量分析调查方法，并比较烟囱研究的整体方法。整个分析是针对在印度北方邦 Aligarh 区 Harduaganj 的 Qasimpur 建造的烟囱进行的。烟囱是任何火力发电厂的突出结构之一，其稳定性确实是使用传统全站仪和其他仪器的一个问题。烟囱的主要功能是以这样的高度和速度将污染物排放到大气中，使被认为对环境有害的污染物浓度保持在地面可接受的范围内。由于无人机系统的发展，调查已经变得非常准确和易于访问。如今，可以更详细地研究结构，也可以使用结构的点云数据进行批判性分析。使用这些点云创建网格表面可用于识别结构中的起伏和缺陷。在本文中，无人机图像和激光雷达数据都用于从两个不同的角度分析相同的结构。使用这两种方法计算结构的偏心率进一步比较精度，