作者：王承瑞
 

数字地籍测量是地籍信息系统的前期工作,其质量的好坏直接影响到地籍信息系统的质量,因此对数字地籍测量过程中的有关问题进行讨论是十分必要的.从地球表面的现实世界的地籍信息到地籍信息系统中的数字化地籍信息,需要进行野外权属调查,数字地籍测量,数字地籍产品质量检验,地籍图数据录入和建库等工作过程,各个环节的质量将直接影响到地籍信息系统的最终质量.本文就地籍信息系统建立前端过程中的有关问题进行讨论.
1 地籍调查中应注意的几个问题
1.1 权属调查表填写
由于权属调查技术性强,工作量大,参与人员多且水平不同等原因,填写后的地籍调查表往往会出现单位名称填写不一致,土地使用性质不统一,相邻宗地四至不衔接,填表字迹潦草或使用简化字等一些情况.特别是一个单位在该区有多块宗地或者是填写宗地四至单位时容易出现此类情况,这将影响到建立信息系统时不能正确地自动的归户;另外,在填写土地使用者性质时,本应填写"全民"或"集体"或"个体"或"个人",而出现了"国营"或"国有"或"私营"这样的名词;还有在填写宗地四至时,如两宗地共用一堵墙时,则只能出现两宗都至墙中,或一宗至墙内另一宗至墙外,但填出了两宗都至墙外或墙内等情况;有的表填写字迹潦草,或使用简化字,让人难以辩认,表的内容而未填写,任意涂改等现象.
为避免上述情况的出现,在实际作业过程中,以街坊划分作业单元,采用"申报——调查——勘测"均在同一时期由同一作业组实施"一步到位"的作业模式,并要求填表时应做到内容填写齐全,用词规范,字迹清楚工整,不得涂改,只能划改,同一内容的划改不得超过两次,划改处应加盖划改人的印章.这样可以有效地防止差,错,漏,做到责任明确,从而达到确保外业权属调查质量的目的.
1.2 共用宗地的处理
一个地块被几个权属单位共同使用,而其间又难以划清权属界线,这样的地块称为共用宗地.对共用宗地的处理方法一是分宗填写地籍调查表,二是只填写一份地籍调查表,在表中注明各权属单位分摊面积.对于前者,共用宗地有多少个土地使用者就填多少份地籍调查表,表上的内容按各分宗的填写.这样做的好处是所填内容详细,调查表和土地登记申请书,审批表形成了一一对应的关系.但其弊端也是显而易见的,其一增大了填表的工作量,其二增大了复杂程度,在填写四至时,如遇一个土地使用者使用几个地块则不得不写清几个地块的四至;为填清界址标示,又得设置内部界址点,增加了宗地草图和地籍图的负荷量,填表时如不小心还会造成表与表之间的相互矛盾.因此应该采取第二种方法,这样可以克服方法一的缺陷.
1.3 特殊宗地的界址点处理
如图1所示,有两个宗地A,B,包含J1,J2,…, J9九个界址点.一般的处理方法是:围成第A宗的界址点为J1,J2,J3,J4,J5,J6,J1;围成B宗其界址点为J2,J7,J8,J9,J2.由于测量误差的存在,J9不一定在界址线J2J3上.若J9在界址线J2J3的右侧,则出现了界址线交叉;若J9在界址线J2J3的左侧,则会出现既不属于宗地A也不属于宗地B的裂隙区域.处理这类问题的办法是,首先在获取界址点坐标时保证J9严格在界址线J2J3上,因为测量误差的存在,如果直接采用坐标测量的方法很难实现,为此可以采用内插方法根据J2,J3点坐标和J3 J9的距离计算J9的坐标,也可采取事后界址点坐标平差处理的方式以保证J9位于界址线J2J3上;其次是正确处理围成宗地的界址点顺序号,一宗地的界址点应该包含该宗地边界线上的全部界址点,例如,围成第A宗的界址点为J1,J2,J9,J3, J4,J5,J6,J1,围成B宗其界址点为J2,J7,J8,J9,J2.这样即使误差的存在也可以保证不会出现重叠(交叉)和裂隙现象.
1.4 提高界址点精度的措施
《规程》对界址点精度的要求是较为严格的,这就要求野外作业者要总结各种有益的经验,提高测量精度.一般来说,我们应该从以下几个方面加以控制.
(1)作业前要严格进行仪器检校.特别是光学对点误差和2C值误差对测量精度产生较大影响.
(2)要严格控制转站.在一般情况下,连续转站不得超过3次,这一点一般都能做到.
(3)因地籍测量一般在城镇且建筑物较密集,所布导线边长都较短,故测站定向时应尽可能选择长边.
(4)碎部测量立镜一定要到位.尽可能采用小棱镜或采用偏心,偏距的方法,使点位无论在什么位置,都能准确测定.
(5)在困难地区.尤其在老居民区,先测外围,利用制高点向内部多打散点,然后用丈量及边长交会等多种方法进行测量.
(6)对隐蔽的界址点可以采用"引点距离交会法"和"直线延伸法" 等测量方法,以提高测量精度.
(7)采用"层层把关,严格检查"的作业制度.为此可以设计解析界址点精度检查表,相邻界址点之间及相邻界址点与地物点之间精度检查表,不相邻界址点之间及不相邻界址点地物点之间精度检查表等三种表格供外业自检及质检部门抽检,并做精度统计.
1.5 界址点测量与数据处理
目前,界址点,地物特征点的数据获取采用全野外解析法进行,通常采用外业数据采集软件进行,如武汉瑞得的RDMS,南方公司的CASS,清华三维的EPSW电子平板等系统.其数据采集的一般过程为:核对界址点,测量界址点及地形点,绘制草图(或输入编码及连接信息),数据录入,数据编辑,地籍图绘制,地籍数据入库.在实际作业中要做到:
(1)先核对地籍元素,然后进行测,算,绘作业,以确保外业权属调查数据的正确;
(2)在作业过程中,应详细绘制草图或记录编码和连接信息;
(3)在连续测算未知点坐标时,随时引入已知点和勘丈边做检核,要注意组合未知点连结条件或已知点条件,以达到互相检核和整条路线检核的目的;
(4)对所有界址点和界址线都做长度检核或坐标校核.
数字地籍测量的界址点和地物点坐标测定时,由于人为或非人为因素的存在,将导致采集的特征点产生误差,甚至粗差.采集误差在一定范围内是允许的,而且可以采取一定的措施加以减弱或消除,但对粗差而言,如果不首先对其进行定位和剔除,则会使特征点之间原有的几何条件遭到破坏.为提高外业测绘成果的精度和可靠性,应对外业测绘成果进行平差处理.实际工作中,不仅要处理单个独立的直角,平行和直线,而且更普遍的情况是对成片房屋(界址)点的处理,由于各种条件混合,各个房屋之间是相关的,显然对单个独立的直角的处理方法已不适用.为此可采用分级控制,逐级平差的方法来处理成片界址点的情况分级平差.根据实测地物复杂程度不同,一般分为l—3级.对于较简单的图形,当考虑的条件方程较少时,不必分级,列出条件方程后统一平差;较复杂的图形可分为2级;对于特别复杂的图形可分为3级.首先以街坊外围界址点为首级控制点,构成一个闭合路线,列出条件方程对其进行平差处理,将平差后的坐标点作为下一级平差的固定点,然后再对成片房屋内部的直角房屋进行平差处理.
2 数字地籍测量产品的质量检验
数字地籍测量是以数字化的方法测定和确定土地及其附着物(也称地籍对象)的位置,权属,数量,质量及利用现状等基本状况的测绘工作.数字地籍测量产品的误差类别可分为地籍对象的几何误差,地籍对象的属性误差,数据逻辑的一致性,地籍数据的时序误差,地籍数据的不完整性误差.
2.1 地籍对象的几何误差检验
几何误差主要指所描述的宗地对象(包括界址点,界址线,行政界线)在特定的高斯投影坐标系中的位置误差,在地籍数据中多用矢量方式以二维平面坐标表达位置,几何误差可分为点误差,线误差及相应点线构成的面积误差.地籍测量数据中界址点,地物点点误差的检验主要采用全站仪,GPS(也可采用RTK技术)等仪器实地检测;线误差的检验以界址线长度检测为主,可用钢卷尺实地丈量检测,表示为一组检测长度与界址线所表达的长度的差值;面积误差的检验主要采用检测的宗地坐标构成的面积与原面积比较.
2.2 地籍对象的属性误差的检验
属性数据可理解为空间对象"是什么",它是地籍对象的特性描述.属性数据的特性描述绝大多数为定性描述,但有时候具有离散性和不确定性,如确定某地块的土地利用现状,它有多种利用类型,在一定程度上面积小的地类将综合到面积大的地类中.地籍属性数据的检验以定性数据评价为主,如地籍数据中一个宗地的属性数据可能包括宗地面积,位置座落,宗地用途,所有人,使用年限,价格,审批表号,发证时间等.属性数据一般为字符串和数字,有的属性项内容较多,较长,为了管理使用方便,管理部门规定对一些属性数据分类和编码,如"土地利用现状"是一种基本的属性,每一地块的"土地利用现状"属性数据,必须按规定的土地利用现状分类和编码系统来确定,相同属性的数据一般放在同一层,以提高管理效率.属性数据采集的方式主要有两种:一种是收集信息对照图形直接输人;另一种是预先建立属性表输人属性或从其他数据库中导人属性,再与几何数据相关联.定性属性数据的检验主要是逐项考核各属性项内容的正确性,属性项字段长度和属性表结构是否正确和完备.
2.3 地籍对象的逻辑不一致性误差检验
数据逻辑的一致性主要指所描述对象间的各种逻辑关系表达的可靠性和正确性,如地理协调性,空间对象相互关系的正确性及其属性描述的合理性.逻辑误差的检验非常重要,它是数据质量控制和质量保证的前提,也是地籍管理系统具备数据查询,统计分析,共享和支持决策所必需的,是检验工作的重要环节.描述地籍对象的矢量数据结构能体现地籍对象之间的空间相互关系,节约计算机存储空间,方便各种数据操作和空间分析.在地籍数据中,逻辑不一致性可能表现为以下方面:(1)一宗地的界址点首尾点不重合;(2)矩形房屋的对角线或对边不相等;(3)整体面积不等于局部面积总和;(4)桥或停车场与道路不相连,道路与道路不相连,导致数据不完整;(5)图面注记与属性表不一致;等等.逻辑不一致性误差检验借助地籍信息系统软件的相关命令进行.
2.4 地籍数据的时序误差检验
地籍数据的采集有时需花较长的时间,不同时间采集的数据客观上会导致许多不一致,数据的现势性跟不上变化,数据反映对象的准确性就降低;反映宗地的各类数据在宗地演变过程中总是处于不断变化之中,如宗地的范围,产权,状态,这些变化更替产生的时序信息应在地籍信息管理系统中合理准确记录,以便能够动态追溯,此类功能的实现也是地籍信息管理系统的重要内容.地籍对象时序信息的查询和检验,可以列出地籍对象属性记录中的相关时序信息逐个检验,或可利用标准数据库查询语言(如结构查询语言SQL)检验指定的对象时序状态.
2.5 地籍数据的不完整性误差检验
地籍数据的完整性指同一要求或精度的数据在指定的项目或测区内数据和资料的完整程度.数据的不完整最简单的例子是数据丢失.如野外测图时测区范围内未测完整,应该采集的各类地形,地物要素有遗漏,属性要素的调查不充分等.另外数据的转换和传输也可能导致数据遗失或畸变.数据的不完整性误差检验可采用综合方法检验,如绘图检验,将分层地籍数据在纸质介质上输出,对照实地或数字化底图检查要素的完整性;屏幕检验,可将各类数据在计算机屏幕上叠加检查要素的完整性及是否有冗余,或将相邻图幅进行拼接检验,确保相邻图幅间的图形和属性完整和连续一致.
3 结束语
数字地籍测量的最终成果质量的好坏直接影响地籍信息系统的质量与可靠性.为提高数字地籍产品的质量,应该在地籍测量的各个时期采取相应措施.本文根据实际工作经验,并参考有关文献,对数字地籍测量产品质量若干问题进行了讨论.在地籍调查中应注意正确处理好权属调查表的填写,共用宗地的处理,特殊宗地的界址点处理,提高界址点精度的措施,界址点测量与数据处理等问题;在外业测绘和内业数据处理过程中应对数字地籍产品中的地籍对象的几何误差,属性误差,数据逻辑的一致性,地籍数据的时序误差以及地籍数据的不完整性误差进行检验,以保证数字地籍产品的质量
 

Digital cadastral cadastral information system is the preliminary work, its quality will have a direct impact on the quality of cadastral information system, so the number of cadastral survey in the process of discussing relevant issues is necessary. From the earth's surface of the real world of cadastral information into the cadastral information system in the digital cadastral information, ownership of the need for field investigations, the digital cadastral survey, the digital cadastral product quality inspection, cadastral map data entry and construction of libraries and other work processes, each link will directly affect the quality of cadastral information system the final quality. This place cadastral information system front-end process of the establishment of the relevant issues for discussion.
A cadastral survey should pay attention to several issues
1.1 Ownership fill in the questionnaire
As the technical nature of ownership of the investigation, the heavy workload involved in many and different levels of personnel and other reasons, fill out a questionnaire after the cadastral unit name will often appear inconsistent fill, land-use nature of the non-uniform, adjacent to four cases of non-convergence, fill in a form illegible handwriting or use of simplified characters and some other situations. In particular, a unit of land in the area were a number of blocks or a complete four units were prone to such a situation, which will affect the establishment of an information system does not automatically go correctly families; In addition, the nature of completing the land users, this should fill in "full" or "collective" or "individual" or "individuals", and emergence of the "state" or "state" or "private" such as nouns; also There were places in completing the four, such as when two to share a wall, then only two have appeared to the wall, or in one case to another wall to wall, but the two have to fill out the wall or walls, etc.; some form fill illegible handwriting, or the use of simplified characters, it was hard identification, the contents of the table without filling, any alteration and so on.
In order to avoid the above situation occurs, in the actual operation process, in order to residents divided operation unit, using the word "declaration - Investigation - Investigation," both in the same period by the same operating group of the implementation of "one step" mode of operation and requested fill in a form the content should be filled complete, standardized terminology, legible neat, can not alter, change can only be drawn, draw the same content to change no more than two designated Department should change to change people's seal stamped classified. This could effectively to prevent the poor, wrong, and missed, so that clearly-defined responsibilities to ensure that foreign trade so as to achieve the purpose of ownership of the quality of investigations.
1.2 share in the handling of cases of
Ownership of a plot by several units in common use, but it has also been difficult to draw the boundaries of ownership, such cases of land known as the common ground. For shared approach were to complete the first sub-case of the cadastral survey, and second, just fill out a cadastral survey, in the table and specify the share ownership of units in an area. For the former, sharing the number of cases to fill in the number of land holdings and land users on the membership questionnaire, the contents of the table by filling in the sub-cases . This has the advantage of the content filled in detailed questionnaires and land registration applications for approval to form a one to one relationship table. but its disadvantages are also obvious, one increases the workload of filling, and the other by great a degree of complexity in completing the four when the case of a few plots of land users have had to use several plots four Xie Qing; to fill clear boundary marking, but also have to set the internal boundary points, an increase of were to sketch and cadastral map capacity, if not careful when you fill in a form table and the table will result in conflicts between. and should therefore adopt the second approach, so that means one can overcome the shortcomings.
1.3 Special cases to deal with the boundary points
Shown in Figure 1, there are two cases in A, B, contains the J1, J2, ..., J9 9 Boundary Point. The general approach is: No. A surrounded by cases of boundary points J1, J2, J3 , J4, J5, J6, J1; surrounded by its boundary point B were J2, J7, J8, J9, J2. due to the presence of measurement error, J9 is not necessarily on the boundary line J2J3. If the boundary line J9 J2J3 the right side, then the emergence of cross-boundary line; if J9 at the left boundary line J2J3 occurs are neither case does not belong to A to B, fissures were regional. to deal with such problems is to first in obtaining an assurance J9 Boundary point coordinates in the boundary line J2J3 strict, because the presence of measurement error, if the method used directly coordinate measurement difficult to achieve, this interpolation method can be used according to J2, J3, Y, and J3 J9 distance from J9 of the coordinates of the calculation can also be taken after the boundary point coordinates adjustment processing method to ensure that J9 is located on the boundary line J2J3; followed by the correct handling of cases of land surrounded by boundary point sequence number, a way The boundary point should be the boundary line that contains the case of all boundary points, for example, the first A surrounded by cases of boundary points J1, J2, J9, J3, J4, J5, J6, J1, surrounded by cases of B the Boundary point J2, J7, J8, J9, J2. so that even if the existence of the error can be guaranteed not to overlap (cross), and fracture phenomena.
1.4 Measures to improve the accuracy of boundary points
"Protocols" right boundary point precision requirement is more stringent, requiring the field operator to sum up the experience of a variety of useful and improve measurement accuracy. Generally speaking, we should control the following aspects.
(1) should strictly carry out pre-operational equipment calibration. In particular, optical pairs of points, error and error of 2C have a significant impact on measurement accuracy.
(2) To strictly control the transfer station. Under normal circumstances, continuous transfer station not more than 3 times, which is generally can be accomplished.
(3) The cadastral survey is generally more dense urban areas and buildings, the side length is shorter wire cloth, so as far as possible options should be directed station long side.
(4) Department of Survey broken mirror legislation must be in place. As far as possible using a small prism or eccentric, offset distance of the ways in which points are located, no matter what position, can be accurately measured.
(5) in the difficult areas. Especially in older neighborhoods, first measure the external use of the high ground to the internal multi-scattered points, and then measured and the side length of intersection of a variety of methods to measure.
(6) on the hidden boundary points can be used "drawing from the intersection point of the Law" and the "straight-line extension of the Law" and other measurements to improve measurement accuracy.
(7) adopt the "Testing at every point, strict inspection" of the operating system. This can be designed to resolve boundary point precision check list, and between adjacent boundary points adjacent to Boundary between the point and surface features-point accuracy check list , and between non-adjacent boundary points adjacent to Boundary Point features in non-point check list accuracy between the three kinds of forms for the self-inspection and quality inspection department, field sampling, and do statistical accuracy.
1.5 Boundary-point measurement and data processing
At present, the boundary points, the feature characteristic point data acquisition using full-field analysis method is usually used, field data collection software, such as Wuhan, Rui obtained RDMS, Southern Company's CASS, Tsinghua EPSW three-dimensional electronic flat-panel systems. the general process of its data collection as follows: check boundary points, boundary points and topographic measurement points, draw sketches (or the input code and connection information), data entry, data editing, cadastral mapping, cadastral data storage. in actual practice in is necessary to accomplish the following:
(1) first check cadastral elements, and then measuring, calculating, painting operations, in order to ensure ownership of the survey data outside the industry, right;
(2) In operating the process should be carefully drawn sketch or record coding and connection information;
(3) estimates the unknown point coordinates in a row when the introduction of a known point and Kan Zhang at any time by doing some checks, pay attention to an unknown combination of known point-point link conditions or conditions to achieve the mutual inspection of nuclear and the whole purpose of inspecting routes ;
(4) for all boundary points and boundary lines so check the length of nuclear or coordinates calibration.
Digital cadastral survey of the boundary points and the feature point coordinates determination, due to the presence of human or non-human factors, will lead to collection of feature points of error, even gross error. Collection error is permitted within a certain range, and can be taken certain measures to be reduced or eliminated, but in terms of gross error, if not the first to locate and remove them, then make between the feature points of the geometric conditions for the destruction of the original. To enhance the accuracy of the results outside the industry, surveying and mapping, and reliability, should be the external sector adjustment deal with surveying and mapping results. actual work, not only to deal with a single independent right-angle, parallel and straight, but more generally the situation is as tablets Housing (boundary) of the treatment, due to various conditions of mixing between the various housing-related, apparently at right angles to a single stand-alone treatment method is not applicable. this can be used hierarchical control, level-adjustment methods to deal with boundary points into a piece of grade level difference. According to the measured features in varying degrees of sophistication, are generally divided into l-3 Ji. For the relatively simple graphics, when considering the conditions when there are fewer equations, without classification, listing the conditions after the reunification of adjustment equation; more complex graphics can be be divided into two; for particularly complex graphics can be divided into three. First of all the external boundary points to neighborhood control points for the first-stage to form a closed line, lists the conditions of equation for adjustment of their treatment, after the adjustment the coordinates points as an adjustment under a fixed-point, and then right into the chip inside the right-angle housing Housing Adjustment for treatment.
2 Digital Cadastral Survey product quality inspection
Digital Cadastral Survey is based on the digital method of measuring and determining the land and fixtures (also known as cadastral objects) location, ownership, quantity, quality and status of the basic status of the use of survey and mapping work. Digital Cadastral Survey of products can be divided into categories of error for the geometric errors of cadastral objects, cadastral object's attributes error, the logical consistency of the data, cadastral data, timing errors, cadastral data, incomplete error.
2.1 The geometric error of cadastral object test
Geometric errors mainly refers to the object as described in cases (including the boundary points, boundary lines, administrative boundaries) in a particular Gauss projection coordinate system the location of errors in the cadastral data in the multi-vector approach to the expression of two-dimensional coordinate position of , geometric errors can be divided into point error, line error and the corresponding points and lines constitute the size of the error. cadastral survey data in the boundary points, features in the test mainly uses little errors Total Station, GPS (also can be used RTK technology) and other equipment with field testing; line error tests to detect the length of the main boundary line, available steel tape measurement field testing, expressed as a set of test length and the length of boundary lines to express the difference; area of the test errors were detected mainly in Coordinate the size composition compared with the original size.
2.2 The cadastral test error of object's properties
Attribute data may be understood as a space object "what", which is the object of cadastral characterization. Attribute data describing the characteristics of the vast majority of qualitative description, but sometimes with a discrete and uncertainties, such as to determine if a plot of land the use of the status quo, it has a variety of use types, to a certain extent, the small size of the land type will be integrated into large area of land class. cadastral attribute data of the test in order to evaluate the main qualitative data, such as the cadastral data in a case of land property data may include cases of land area, location is located, cases of land use, owners, life, price, approval form number, certification time. attribute data is usually a string and numbers, and some properties of items in more than long, easy to manage, management provides for a number of properties data classification and coding, such as "land use status quo" is a basic attribute of each block of the "land use status quo" attribute data, must be provided for land-use status of classification and coding system to identify the same property data are generally in the same layer in order to improve management efficiency. attribute data collected, there are two main methods: one is to gather information directly to the input control graphics; the other is pre-established Property sheet input attributes or leaders from other database attributes, and then the data associated with the geometry. qualitative test of attribute data is mainly one by one assessment element of the correctness of each attribute, attribute length and attribute table entry field structure is correct and complete.
2.3 The logical inconsistency of cadastral object error test
Mainly refers to the logical consistency of the data described in a variety of logical relationship between objects to express the reliability and validity, such as geographical coordination, the correctness of the relationship between spatial objects and their properties are described as reasonable. The logical error of the test is very important , which is the data quality control and quality assurance of the premise, but also cadastral management system with data query, statistical analysis, sharing and support decision-making necessary, is an important part of inspection work. cadastral description of the object vector data structure can reflect the object of cadastral the space between the relationship between the saving computer storage space and convenience for a variety of data manipulation and spatial analysis. cadastral data, the logical inconsistency may appear to be the following: (1) a land point of beginning and end points do not coincide Boundary; (2) The rectangular housing or the right side of the diagonal are not equal; (3) of the total area is not equal to the sum of local area; (4) bridge or a car park and road are not connected to roads and road are not connected, resulting in incomplete data; ( 5) Note on the surface are inconsistent with the attribute table; and so on. the logical inconsistency of the error test cadastral information system software with the relevant commands.
2.4 The cadastral data timing error of test
Cadastral data collection is sometimes required to spend a long time, the data collected at different times objective will lead to a number of inconsistencies, the data can not keep up the current trend of changes in, the figures show the accuracy of the object on the reduced; reflect the types of data in cases of land cases in the evolution is always in flux, such as the scope of cases of land, property rights, status, these changes change the timing information should be generated in the Cadastral Information Management System reasonably accurate records in order to be able to dynamically trace of such features implementation is Cadastral Information Management System for important content. cadastral object timing information inquiry and inspection, you can list the object properties of the cadastral records related to timing of information one by one for inspection, or can make use of standard database query language (such as structured query language SQL) test specified timing state of the object.
2.5 cadastral data integrity error test of non -
Cadastral data integrity refers to the same requirements or accuracy of the data in the specified project or test the integrity of data and information on the district level. Data is incomplete simplest example is the loss of data. As time field mapping was not detected within the surveyed area, a full , it should be collecting all kinds of terrain features and physical objects are missing, the property is not sufficient and other elements of the investigation. In addition data conversion and transmission may also lead to data loss or distortion. error of testing the integrity of the data can be used without an integrated approach to inspection, such as the drawing test, the cadastral data in the paper layered media output, the control on the ground or digital base map check the integrity of the elements; screen testing, various types of data can be superimposed on the computer screen check the elements of integrity and whether there is redundancy , or spliced adjacent map sheet for inspection to ensure that the adjacent map sheet between the graphics and attributes complete and coherent.
3 Conclusion
Digital Cadastral Survey of the final outcome of a direct impact on the quality of cadastral information system for quality and reliability. To enhance the product quality digital cadastral, cadastral survey should take corresponding measures in all periods. Based on the practical work experience and references to other documents of digital cadastral product quality a number of issues were discussed. cadastral surveys should pay attention to correctly handle the ownership of the completed questionnaire, common to the handling of cases, special cases of land boundary point of treatment, to improve the accuracy of boundary points measures, Boundary-point measurement and data processing problems; outside the industry, mapping and data processing within the industry in response to Digital Cadastral products cadastral object geometric errors, attribute errors, the logical consistency of the data, cadastral data, timing errors, as well as the cadastral the integrity of the data errors are not tested to ensure product quality digital cadastral