Circular No. 69/2015/TT-BTNMT on technical procedures for updating the geographic base database at a scale of 1:10,000 using satellite imagery

CIRCULAR

Technical regulations for updating the geographic base database at a scale of 1:10,000 using satellite images pursuant to Decision No. 3/NĐ-CP dated March 4, 2013 of the Government on the functions, tasks, powers, and organizational structure of the Ministry of Natural Resources and Environment;

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/NĐ-CP of the Government stipulating the functions, tasks, powers, and organizational structure of the State Bank of Vietnam;1/201Pursuant to Decree No. 45/2015/NĐ-CP dated May 6, 2015 of the Government on surveying and mapping activities;

At the proposal of the Director of the Vietnam National Survey and Mapping Center, the Head of the Legal Department, and the Head of the Science and Technology Department;ồ;

The Minister of Natural Resources and Environment issues this Circular providing technical regulations for updating the geographic base database at a scale of 1:10,000 using satellite images.

This Circular provides technical regulations for updating the geographic base database at a scale of 1:10,000 using satellite images.and 20 billion VND at the rate of 4.9%/year, and thus, Commercial Bank A This Circular applies to state management agencies; organizations and individuals related to the updating of the geographic base database at a scale of 1:10,000 using satellite images within the territory of Vietnam.

PART I

GENERAL PROVISIONS

Article 1. Scope of Regulation

1. Pixel of image is the smallest element of an image recordable on the sensor device of the image receiver.

Article 2. Applicability

2. Ground resolution of satellite images is the size of one pixel of a satellite image projected onto the ground.

Article 3. Explanation of Terms

In this Circular, the following terms shall be understood as follows:

3. Nominal resolution of satellite images is the theoretical resolution of images published by commercial satellite image providers in technical specifications of that type of satellite images.

4. Satellite image map is a digital satellite image product positioned in the coordinate system of the map to be established, corrected for terrain elevation effects, resampled according to the nominal resolution of the satellite image, cut and joined according to map sheets, and named according to the corresponding map sheet designation.

5. Digital Terrain Model (DTM) is a numerical model representing the shape of the terrain surface.

6. GeoTIFF format is a special file format for storing digital image data with accompanying geographic location information of the image.

7. TIN (Triangulated Irregular Network) format is a type of format used to store digital terrain models as a network of irregular triangles.

8. GRID format is a special format used to store digital elevation models and digital terrain models in a square grid pattern, which can be in binary or ASCII (American Standard Code for Information Interchange) file formats.

9. Metadata, commonly referred to as descriptive data, are information describing characteristics of data such as content, format, quality, conditions, and other attributes to guide access methods, managing authorities, access addresses, storage locations, and data preservation.

Article 4. Frequency and extent of updating the geographic base database

Based on the degree of change and requirements for managing the content of the geographic base database, the frequency and extent of updating the geographic base database at a scale of 1:10,000 using satellite images shall be implemented in accordance with Article 4 of Circular No. 10/2013/TT-BTNMT dated May 28, 2013 of the Ministry of Natural Resources and Environment on technical regulations for updating the geographic base database at scales of 1:2000, 1:5000, and 1:10000 (hereinafter referred to as Circular No. 10/2013/TT-BTNMT).

Article 4. Frequency and extent of updating the geographic base database

Based on the degree of change and management requirements for the content of the geographic base database, the frequency and extent of updating the geographic base database at a scale of 1:10,000 using satellite imagery shall be carried out in accordance with the provisions of Article 4 of Circular No. 10/2013/TT-BTNMT dated May 28, 2013 of the Ministry of Natural Resources and Environment stipulating technical regulations for updating the geographic base database at scales of 1:2000, 1:5000, and 1:10,000 (hereinafter referred to as Circular No. 10/2013/TT-BTNMT).

Article 5. Content of updating the geographic base database at a scale of 1:10,000 using satellite images

The content of updating the geographic base database at a scale of 1:10,000 using satellite images includes the following main tasks:

1. Preparation work, including:

a) Preparing materials and equipment, technology;

b) Studying the situation of changes in the area for updating the geographic base database at a scale of 1:10,000;

c) Surveying the degree of change in the content of the original geographic base database at a scale of 1:10,000;

d) Field survey;

đ) Developing Technical Design - Budget Estimate;

e) Extracting the geographic base database to serve the update.

2. Updating the geographic base database at a scale of 1:10,000, including:

a) Collecting geographic data at a scale of 1:10,000 using satellite images;

b) Standardizing data.

3. Synchronizing and integrating the geographic base database at a scale of 1:10,000.

4. Testing, acceptance, and packaging the product.

Chapter II

PREPARATION WORK

Article 6. Preparation of materials and technological equipment

The preparation of materials for updating the geographic base database at a scale of 1:10,000 using satellite images includes:

1. Preparing satellite image materials with a pixel size not exceeding 2.5 meters, taken or captured at the nearest time point, no more than one year before the update date, to serve the survey of changes in the content of the original geographic base database at a scale of 1:10,000.

2. Preparing measurement and map data and other specialized materials.

3. Collecting relevant legal normative documents related to the geographic base database.

4. Preparing technology, equipment, and human resources for implementation.

Article 7. Study of the situation of changes in the area for updating the geographic base database at a scale of 1:10,000

The study of the situation of changes in the area for updating the geographic base database at a scale of 1:10,000 shall be carried out in accordance with Article 7 of Circular No. 10/2013/TT-BTNMT.

Article 8. Surveying the degree of change in the content of the original geographic base database at a scale of 1:10,000

1. Reviewing the technical regulations that have changed between newly issued technical documents related to the geographic base database at a scale of 1:10,000 and the regulations already applied to build the geographic base database.

2. Evaluating the completeness, reliability, and degree of change in geographic object information of the original geographic base database at a scale of 1:10,000 by comparing and contrasting the content of the original geographic base data with the satellite image materials used, measurement and map data, and other specialized materials.

3. Conducting field surveys according to Articles 7 and 9 of this Circular.

4. The evaluation results must provide conclusions on the level of update and the method of updating the original geographic base database using satellite images selected.

Article 9. Field survey

Field surveys are conducted point-by-point and along routes. Before conducting the survey, a survey diagram must be prepared, marking the positions of points and routes to be surveyed and developing a deployment plan. The objectives of the field survey are:

1. To supplement the internal research on the situation of changes in the update area;

2. To supplement the internal assessment of the original geographic base database;

3. To collect local materials; survey the current status of coordinate and elevation control points used for photograph control (if any).

Article 10. Preparation of Technical Design - Budget Estimate

Clause 1. The Technical Design - Budget Estimate shall be prepared based on survey results and in accordance with the regulations of the competent authority.

Clause 2. The Technical Design - Budget Estimate shall be used for construction, inspection, acceptance of products, and settlement of accounts for projects after being approved by the competent authority.

Clause 3. The contents of the Technical Design - Budget Estimate shall be implemented in accordance with the Management Regulations for Programs, Projects, and Specialized Tasks under the Ministry of Natural Resources and Environment.

Article 11. Extracting Geographic Base Data

Clause 1. The extraction of geographic base data can only be carried out after obtaining a decision approving the content of the work to update from the competent authority.

Clause 2. The Vietnam National Survey and Mapping Center shall be responsible for extracting geographic base data in accordance with the regulations.

Chapter III

UPDATE OF THE GEOGRAPHIC BASE DATA AT SCALE 1:10,000

Article 12. General Requirements

The level of detail of the content of the geographic base data, spatial accuracy, and temporal accuracy of the geographic objects collected for updating the geographic base data at scale 1:10,000, standardization of the geographic base data shall be carried out in accordance with the Regulation on Collecting Geographic Base Data at Scale 1:10,000 in Appendix 2 of Circular No. 21/2014/TT-BTNMT issued by the Ministry of Natural Resources and Environment on April 24, 2014 (hereinafter referred to as Circular No. 21/2014/TT-BTNMT).

Article 13. Collection of Geographic Data at Scale 1:10,000 Using Satellite Images

Clause 1. Satellite images used for updating the geographic base data at scale 1:10,000 must have a ground resolution of less than or equal to 1 meter (0.1 millimeters according to map scale); the use of single satellite image scenes with a ground resolution up to 1.5 meters is only applicable when permitted by the competent authority in certain special cases such as small areas requiring updates without terrain elements.

Clause 2. Satellite images used for updating the geographic base data must be taken at the latest possible time, not more than one year before the update date.

Clause 3. Single satellite image scenes should be used to collect geographic objects for updating the geographic base data in areas where there is no significant change in topography or minor changes in topography.

Clause 4. In areas with significant changes in topography, stereoscopic satellite images must be used to collect geographic objects, specifically:

Point a) Areas on the map that require representation of basic contour lines at intervals of 2.5 meters must use stereoscopic satellite images with a ground resolution of less than or equal to 0.5 meters;

Point b) Areas on the map that require representation of basic contour lines at intervals of 5 meters must use stereoscopic satellite images with a ground resolution of less than or equal to 1 meter.

Clause 5. The collection of geographic data using satellite images must ensure technical requirements for each step of the process in accordance with current technical regulations, including the following main steps:

Point a) Design and control point measurement for external field photography;

Point b) Internal field densification of control points (scene modeling, block modeling);

Point c) Stereoscopic drawing on digital photogrammetry stations for geographic objects in cases where stereoscopic satellite image pairs are used;

Point d) Establishment of digital terrain models (for cases where stereoscopic satellite image pairs are used);

Point đ) Establishment of satellite image plans;

Point e) Vectorization of geographic objects on satellite image plans;

Point g) Field investigation and supplementary measurements of geographic objects.

Article 14. Design and connection control point measurement for non-aerial photography images

1. Each image scene must be arranged with at least 12 non-aerial photography control points, their positions should be relatively evenly distributed and not too close to the edge of the image scene. In the overlapping area between adjacent image scenes, there must be at least 2 non-aerial photography control points.

2. Each image scene must have at least 2 check points, located alternately among the control points. The coordinates and height of the check points must be determined with accuracy equivalent to that of the non-aerial photography control points.

3. Non-aerial photography control points and check points selected must exist on-site and have clear images on the photograph, ensuring they are easily recognizable and marked on the photograph. If selecting points at the intersection of linear features, the angle of intersection must be within 30° to 150°; if selecting points on circular features, the diameter of the feature must be less than 0.3mm on the photograph. In addition to these requirements, the position of the selected non-aerial photography control points must ensure convenience for connection work.

4. Mark the positions of non-aerial photography control points and check points by driving wooden stakes or iron stakes into the ground, or using paint to mark the positions on-site, ensuring stability during construction and inspection.

5. Non-aerial photography control points and check points must be punched onto the control photograph at the actual site, with the punch hole diameter not exceeding 0.15mm on the photograph. National coordinate and height points used as the basis for non-aerial photography control connection must also be punched onto the photograph like non-aerial photography control points if they can be identified on the photograph.

6. All punches on the control photograph must be corrected on both sides of the photograph. On the front side of the photograph, the points are circled and named; on the back side, a diagram noting the points including an overview diagram and a detailed location description diagram is drawn. The correction method follows the model specified in Appendix 1 of the Technical Regulations for Establishing Topographic Maps at Scales of 1:10,000, 1:25,000, and 1:50,000 using digital imagery technology.

7. Non-aerial photography control connection work is carried out according to the technical regulations of the Technical Regulations for Establishing Topographic Maps at Scales of 1:10,000, 1:25,000, and 1:50,000 using digital imagery technology.

Article 15. Thickening Control Points for Aerial Photography (Scene Modeling, Block Modeling)

1. Input satellite image data, select the mathematical model of the satellite image sensor: physical model or rational function model depending on the input image data.

2. Declare and set up correctly all coordinate system parameters and map projection methods.

3. Set the image point measurement error value to ±0.3 times the size of the image pixel.

4. Measure the non-aerial photography control points and check points on the satellite image scenes. The residual distortion at each point must not exceed ±1 times the size of the image pixel;

5. Measure the image tie points:

a) Measure the image coordinates of distinct ground features appearing in the overlapping areas between satellite image scenes;

b) There is no need to measure image tie points when adjacent satellite image scenes are part of the same scan strip;

c) For blocks consisting of single satellite image scenes, at least 3 tie points must be measured in each overlapping area of the satellite image scenes, ensuring they do not lie on a straight line or nearly on a straight line;

d) For blocks consisting of stereo pairs of satellite image scenes, tie points must be selected to be relatively evenly distributed across the surface of each stereo model. Each stereo pair must measure at least 6 tie points;

đ) The residual distortion at each tie point must not exceed ±1 times the size of the image pixel.

6. Block adjustment thickening errors: The block adjustment results for satellite images must meet the following accuracy requirements:

a) Root mean square weighted error (sigma naught): must not exceed ±1 times the size of the image pixel;

b) The root mean square positional error of the non-aerial photography control points after block adjustment thickening must not exceed ±1.5 times the size of the image pixel, and the root mean square height error must not exceed 1/3 of the basic height difference;

c) The difference between the thickened coordinates and heights and the measured non-aerial photography coordinates and heights of the check points must not exceed ±1.5 times the size of the image pixel in planimetric terms and 1/3 of the basic height difference in height terms;

d) The root mean square positional error of the thickened internal photography points must not exceed ±1.5 times the size of the image pixel, and the root mean square height error of the thickened internal photography points compared to the nearest geodetic control point must not exceed 1/3 of the basic height difference;

đ) The limit positional and height error of the thickened internal photography points is defined as twice the errors in Point d, Clause 6;

e) The largest error must not exceed the limit error, and the number of errors exceeding the limit but smaller than the limit error must not exceed: in planimetric terms: 5% of the total cases; in height terms: 5% of the total cases for plains and hills; 10% of the total cases for mountains and high mountains and hidden areas;

g) Block boundary error: the difference in positional error of the thickened internal photography points within the overlapping area of two adjacent satellite image blocks must not exceed 0.4mm according to the map scale, and the height difference must not exceed half of the basic contour interval.

Article 16. Stereoscopic measurement on digital image stations for geographic objects using stereoscopic satellite image pairs

The stereoscopic measurement of geographic objects on digital image stations shall comply with technical regulations set forth in Point 4.6.1 of the Technical Regulations for Creating Topographic Maps at scales of 1:10,000, 1:25,000, and 1:50,000 using Digital Image Technology and Data Collection Regulations for Geographic Base Maps at a scale of 1:10,000 as stipulated in Appendix 2 of Circular No. 21/2014/TT-BTNMT.

Article 17. Establishment of Digital Terrain Models for cases using stereoscopic satellite image pairs

1. A Digital Terrain Model (DTM) is established to represent the landform of the area to be updated and to support satellite image rectification.

2. The Digital Terrain Model (DTM) is established based on detailed measurements of terrain features including drainage lines, watersheds, elevated and depressed landforms, characteristic elevation points, contour lines, and other related elements combined with point elevation grid measurements.

3. The accuracy of elements participating in the construction of the Digital Terrain Model must comply with the provisions set forth in Point 2.4 of the Technical Regulations for Creating Topographic Maps at scales of 1:10,000, 1:25,000, and 1:50,000 using Digital Image Technology.

4. The Digital Terrain Model is established in TIN or GRID format and stored in separate files named according to the corresponding map sheet nomenclature to serve the representation of the landform.

5. The Digital Terrain Model is converted to raster format for use in satellite image rectification with pixel size requirements as follows:

a) The pixel size of the raster Digital Terrain Model does not exceed 8m x 8m for areas on maps requiring basic contour lines of 2.5m and satellite images used having ground resolution less than or equal to 0.5m.

b) The pixel size of the raster Digital Terrain Model does not exceed 16m x 16m for areas on maps requiring basic contour lines of 5m and satellite images used having ground resolution of 1m.

Article 18. Establishment of Satellite Image Orthomaps

1. Use digital elevation models and digital terrain models to rectify satellite images when the displacement of image points caused by terrain elevation differences is greater than or equal to 0.3mm according to the required map scale. If the displacement of image points caused by terrain elevation differences is less than 0.3mm, then use the average elevation of the area to rectify the images.

2. In cases where high-resolution stereoscopic satellite image pairs are used, the digital terrain model established in accordance with Clause 5 of Article 17 of this Circular shall be used to rectify satellite images.

3. In cases where single scene images are used, existing digital elevation models and digital terrain models from previous geographic base data projects shall be utilized to rectify the images.

4. Digital elevation models and digital terrain models must be adjusted for height in areas with tall trees, dense vegetation, and areas with large architectural structures to ensure that there is no distortion or image sliding on the orthomaps.

5. Satellite images are rectified on a per-scene basis. Orthomaps are stored in GeoTIFF format with the pixel size of the orthomaps being equal to the nominal resolution of the input satellite images, or not exceeding 1m.

6. Requirements for planimetric accuracy of orthomaps are as follows:

a) Planimetric positional error of control points and check points on the orthomaps must not exceed ±4m (0.4mm calculated according to the scale of 1:10,000).

b) Mutual positional errors of objects within the overlapping areas between scenes: not exceeding ±4m for clear objects and not exceeding ±6m for unclear objects.

7. When the input satellite scenes include both full-color (black and white) and multispectral images, a natural color composite image must be created. To ensure that objects on the natural orthomaps have sharp and clear images, the full-color orthomaps should be used as control images during modeling for rectifying multispectral images.

8. Cutting and joining frames of satellite orthomaps to be established:

a) When the frame of the satellite orthomap to be established lies across multiple scenes, image stitching must be performed.

b) Image stitching lines must not follow linear geographic features or shaded areas on the images.

c) Stitched images must not reveal stitching lines, ensuring clarity, brightness, contrast, harmonious colors, and uniformity with surrounding orthomap frames.

d) Frames of satellite orthomaps are cut according to the nomenclature of topographic map sheets at a scale of 1/10,000, ensuring a 1cm overlap along each side, and stored in GeoTIFF format; the file name of the satellite orthomap frames is identical to the name of the topographic map sheets to be established.

9. Frame of the satellite orthomap (used for drawing images) includes inner and outer frames similar to those of the topographic map to be established, comprising:

a) Orthomap frame, geographic coordinates, and orthogonal coordinates.

b) Name and designation of the satellite orthomap frame.

c) Scale of the established satellite orthomap.

d) Boundary diagram.

đ) Information about satellite images (type of image, resolution, and time of capture).

e) Name of the unit and time of establishment of the satellite orthomap.

g) Coordinate system of the satellite orthomap.

10. Storage of digital orthomaps: Each frame of the digital orthomap is stored in separate directories, with each directory named after the designation of each topographic map sheet. Within each directory, there are GeoTIFF format orthomap files and boundary orthomap files established as per Clause 9 of this Article.

Article 19. Vectorization of geographic objects on satellite image maps

The vectorization of geographic objects on satellite image maps shall comply with technical regulations set forth in Point 4.7 of the Technical Regulations for Establishing Topographic Maps at Scale 1:10,000; 1:25,000 and 1:50,000 using Digital Image Technology and the Data Collection Regulations for Geographic Base Maps at Scale 1:10,000 in Appendix 2 of Circular No. 21/2014/TT-BTNMT.

Article 20. Surveying of Geographic Objects and Supplemental Field Mapping

1. Internal surveying of geographic objects from documentation, measurement data, and maps, specialized documents and data includes the following steps:

a) Analyzing and evaluating documentation and data according to the requirements for content updates;

b) Developing guidelines for collecting geographic data;

c) In cases where multi-spectral satellite imagery channels are used, remote sensing techniques must be applied in conjunction with existing geographic base databases to build image interpretation tools to enhance the effectiveness of internal mapping and image interpretation work, such as: building image interpretation keys for certain surface cover types; creating difference index water channels, difference index vegetation channels; other composite color images (if applicable);

d) Preparing field survey instructions.

2. External surveying of geographic objects must follow the Data Collection Regulations for Geographic Base Maps at Scale 1:10,000 in Appendix 2 of Circular No. 21/2014/TT-BTNMT, including the following steps:

a) Checking, verifying, supplementing, and editing to accurately finalize results prepared internally;

b) Surveying attribute information for various types of geographic objects according to the list of geographic object categories at scale 1:10,000.

3. Detailed supplementary mapping of geographic objects for areas with old images or poor quality images due to cloud cover or glare shall comply with the provisions set forth in Point 4.4.7 of the Technical Regulations for Establishing Topographic Maps at Scale 1:10,000; 1:25,000 and 1:50,000 using Digital Image Technology.

Article 21. Standardizing Updated Geographic Base Database

1. Spatial standardization for geographic objects in the extracted copies of the geographic base database, including: adding new emerging objects, revising changed objects, deleting non-existent objects on-site, standardizing spatial relationships between geographic objects.

2. Attribute standardization of geographic objects according to current technical regulations.

3. Relationship standardization of geographic objects according to current technical regulations.

4. Standardizing data formats to facilitate synchronization and integration of updated copies of the geographic base database into the original geographic base database at scale 1:10,000.

5. Standardizing metadata according to updated contents.

Chapter IV SYNCHRONIZATION AND INTEGRATION OF GEOGRAPHIC BASE DATABASES

Article 22. Synchronization of Updated Copies of Geographic Base Databases with Original Geographic Base Databases

The synchronization of updated copies of geographic base databases with original geographic base databases includes the following main steps:

1. Updating spatial and attribute data.

2. Synchronizing geographic objects in terms of space and attributes.

3. Updating relationships among geographic objects within the same scale category.

4. Updating relationships among geographic objects across different scale categories.

Article 23. Integration of extracts from updated geographic base database into the original geographic base database

The integration of the geographic base database at a scale of 1:10,000 shall comply with the provisions set forth in Chapter IV of Circular No. 10/2013/TT-BTNMT.

Chapter V

TESTING AND PACKAGING OF PRODUCTS

Article 24. General Requirements

Quality control testing for products updating the geographic base database shall be carried out in accordance with Circular No. 63/2015/TT-BTNMT dated December 21, 2015 of the Ministry of Natural Resources and Environment on inspection, evaluation, and acceptance of quality of surveying and mapping works and products.

Article 25. Content of Testing and Acceptance, Packaging of Products Updating the Geographic Base Database

1. Testing and acceptance of results of control point measurement for aerial photography: control photos; diagrams of control point connection for aerial photography; testing materials for surveying equipment; measurements; calculation results of control network adjustment for aerial photography.

2. Testing and acceptance of results of block densification error propagation calculation.

3. Testing and acceptance of digital terrain model product.

4. Testing and acceptance of satellite image orthophoto product.

5. Testing and acceptance of results of geographic object mapping: stereoscopic mapping results and vectorization results on satellite image orthophotos.

6. Testing and acceptance of results of geographic object investigation and supplementary fieldwork mapping.

7. The testing and acceptance, packaging of products updating the geographic base database shall be conducted according to each work item and upon completion of the entire geographic base database update process, including the following main steps:

a) Testing and acceptance, packaging of extracts from the updated geographic base database.

b) Testing and acceptance of synchronization of extracts from the updated geographic base database with the original geographic base database in accordance with technical regulations for geographic base databases at corresponding scales.

c) Testing and acceptance of integration into the original geographic base database in accordance with national geographic base database management system technical regulations.

8. Product packaging for updating the geographic base database must ensure that the data scope is correct according to the extracted boundaries; data format according to the extract format.

Chapter VI

IMPLEMENTING PROVISIONS

Article 26. Effective Date and Implementation

1. This Circular takes effect from February 15, 2016.

2. The Vietnam National Survey and Mapping Center shall be responsible for monitoring the implementation of this Circular.

3. In the course of implementation, if there are any difficulties, agencies, organizations, and individuals shall promptly report to the Ministry of Natural Resources and Environment for consideration and decision./.