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International Archives of the Photogrammetry, Remote Sensing and Spatial Informatiofi Sciences, Vol XXXV, Part B2. Istanbul 2004
e Audit quality in every activity;
eFault and process registering, when detected —
documentation;
eImplementation of corrective actions when detected in
the production chain.
- Work Instructions: Every activity must be executed in
function of specification's requirement. The registered
instructions will allow implementing the company know-how,
making it less susceptible to unexpected problems that can
occur during production process. It makes possible also, to
define a work severity that will guarantee the quality control
to the customer.
— Corrective Actions: Quality control means error reduction or
elimination. The corrective actions documentation serves as a
registering of efforts carried out in order to obtain the desired
quality. The main objective is to eliminate or to prevent the
causes of nonconformity or imperfections in the spatial data
production processes. These actions are registered with the
purpose of keeping a description of the quality.
The Quality Control Systems workflow for Digital
Photogrammetric Processing (PQCS) is presented in Figure 2.
Two steps compose PQCS: (i) procedure description and (ii)
quality analysis.
Oualitv Control Procedures - Part I
Concept Model
Graphical Model
Procedures Work
Description Flow
— Applied Processes: As they are applied, they are registered
in form of reports and printed in the graphical project and also
m as table for activities control.
| | | — Conceptual Model: The adoption of a data conceptual model
Regulamentations Fe »| Working | | Perform during the negotiation phase must lead to a "prototype" of the
|
Specifications on Seek ; Cane RT. .
Instruetons Process product in order to facilitate the definition of the product and
| to adequate it for use or to make it adjusted to the customer's
necessities.
Quality Analysis - Part II ; : : 2.1.2 Quality Analysis
Quality Control QC = VISUAL CHECK The second PQCS step is based on some Suisse
€ J À x T SEU E - . ^ * *
: , i : stives (draft version) Al with ac
fine Prodruction DOCUMVENTATION photogrammetric directi es (draft version) It deals with aero
A : phtogrammetric process including image shooting, processing
ans “Quality CORRECTIONS and scanning; terrestrial control points, aerotriangulation, DTM
Aquisition Parameters -— - REGISTER generation, ortophotos generation and vectorization. The main
quality items observed in the system are presented in annexed
Dd Table 1.
; ; ; ity Par IS
Scanning | | 7 Scanner v Tonal
= Qc? Calibration Y Pixel Sizel
= + V Camera 2.1.2.1 Quality Control and Vectorization
= Project * Brighteness For horizontal and vertical positioning quality control during
em Preparation v Contrast vectorization the Eslami Rad (1995) recommendation is used,
ontro
as described in Equations 1 and 2 on Table 1. The sigma values
are the same as presented in that table.
Y
Images files | r9] Interior Orientation 2.2 Attributes Accuracy and Completeness
Camera Data
: QC The implementation of a logical model including topological
: S restriction definition in the created classes and the
Image Sequencies ^d Aerial : . Sis mm ; .
Flight Data Pb Tiangulation implementation of visualization methods must avoid logical
consistency errors in the database. For instance, permissible
values are established to avoid the occurrence of “overshoots” e
DTM Generation |4——.: us ei - :
e undershoots" phenomena. The first one can be explained, as
Vectorizati for instance, as a line that can surpass an intersection during a
BI ectorization , c
P roduct vectorization process. The second one can be explained, as for
Ortophoto Quality ———— no dure t /oid : lines d Iygons being
Cnn ality instance, as a procedure to avoid arcs, lines and polygons being
I too far way from neighbor elements.
Figure 2 Functionality workflow of the PQCS : ; Ja)
Other established rules are configured in the digital
photogrammetric system in such a way to alert the operator if
any restricted action is taken. The proposed basic rules consider
the following factors:
2.1.1 Procedure Description
This part of the system includes all documents that must be
issued in order to guarantee a high level of quality. The
following are the principal parameters to be considered in that
control phase: eParallelism between lines (road edges, canals,...);
eLines perpendicularity (building edges...);
eNon duplicated lines or polygons;
e Input acceptance for layers, color, etc;
eMinimal proximity for lines;
eMinimal polygon dimension;
eMinimal squaring;
e Automatic polygons closing.
— Specifications: The existing technical specifications shall be
translated to the operational level under the form of
spreadsheets graphically indexed and workflow diagrams
contemplating graphical illustrations of the instructions.
— Regulations: All norms, regulations or requirements of the
specifications inherent to the execution of the mapping
project are placed in first plan during activities planning and
quality control measurement specifications. An example on how to proceed for data collection automation
restriction was implemented on a data object oriented system
797
