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Chapter D13 ver. 1

Basemapping

Table of Contents

Effective Date

This Chapter is effective January 1, 1997. It was originally published as Chapter D13 of the Third Edition of the Manual of Instructions for the Survey of Canada Lands.

Chapter Sections

General

  1. This Chapter applies to the mapping of base maps (basemapping) which supports legal surveys of Canada Lands.
  2. Specific survey instructions are issued for basemapping carried out under this Chapter.
  3. Basemapping carried out under this Chapter should be done under the supervision of a Canada Lands Surveyor or, with the permission of the Surveyor General Branch, a land surveyor commissioned to survey lands in the province in which the survey is located.
  4. Control surveys carried out for basemapping should conform to Chapter D12.

Photography and Targeting

  1. All aerial photography used in any mapping project shall conform to the specifications of the Interdepartmental Committee on Air Surveys (ICAS) and will be recorded in the National Air Photo Library. Photography of record in provincial or territorial photo libraries will also be accepted providing it will meet ICAS specifications.
  2. Control points to be targeted for aerial triangulation and numerical adjustment, and monuments to be targeted to facilitate registration (overlaying) of legal survey boundary information with mapping detail, will be specified in the specific instructions for the mapping.
  3. Targeting shall be of sufficient size and contrast to be visible on the final base map.
  4. The surveyor is responsible for obtaining permission to place targets on private property, for removing the targets and for any damage caused during the course of the work.

Mapping

  1. The projection system for mapping should be the official system used in the province or territory in which the mapping is located.
  2. The datum plane for contours should be mean sea level as defined by Geodetic Survey Division, Natural Resources Canada.
  3. Map sheet size, location of image area, overlap of map detail, location of title block and other requirements may vary from one province or territory to another. Regional requirements will be outlined in the specific instructions.
  4. For base maps that are to be registered with cadastral survey or other positional information the minimum accuracy requirement is as follows:
    1. ninety-five percent of all map information must be shown within 0.5 mm of the true position of the information on the map; and
    2. all remaining map information must be shown within 1.0 mm of the true position.
  5. The following table shows absolute accuracy requirements for recommended map scales. The accuracy selected should be for the largest scale the mapping is likely to be used.
    Absolute Accuracy Requirements
    Recommended Scale Accuracy Requirement
    1: 1,000 0.5 m
    1: 2,000 1.0 m
    1: 5,000 2.5 m
    1: 10,000 5.0 m
    1: 20,000 10.0 m
  6. Map sheets should be oriented so the top of the sheet is North or approximately North. A north arrow shall be placed on the base map.
  7. Where a base map is to be manually registered with a cadastral or other overlay the HARRIS Registration System shall be used unless otherwise specified in the specific survey instructions. Registration will be along the north edge of the base map and the overlays. The use of tabs or pre-punched register strips is not permitted.
  8. The base map shall show a grid system preferably consisting of "edge ticks" around the perimeter of the image area and crosses on the interior of the map. Grid intervals shall be at a minimum of 10 cm. North/ South grid coordinate values shall be displayed along the left edge of the image area and East/ West coordinate values shall be displayed along the bottom edge of the image area.
  9. Grid lines shall be determined by relating the theoretical grid lines to geodetic control survey markers or to other acceptable control, the position of which is known in relationship to the map detail.
  10. The base map shall show official names of places and natural features according to the federal, provincial or territorial edition of the Gazetteer of Canada, published government maps or, if no official name exists, local usage.
  11. Lettering shall be typeset, scribed or made using digital fonts.
  12. Provide in the title of the map:
    1. a description of the area mapped;
    2. the scale and a scale bar; and
    3. the date of compilation.
  13. Provide in the legend of the map:
    1. the coordinate datum used, the type of projection, the central meridian, and the zone; and
    2. the identification numbers and source of the photographs used in the compilation.
  14. Provide at the top right hand corner of the map a 5 cm x 8 cm block for recording information.

Photomaps

  1. The degree of contrast and density of a photomap assembly shall be controlled by a densitometer. The minimum density should not be less than 0.2 and the maximum density should not exceed 1.2. The contrast should be in the range 0.8 to 1.0.
  2. Photographs shall be selected to avoid specular reflection from water surfaces wherever possible. In the event that some reflection cannot be avoided, the water areas affected shall be re-touched in the assembly, so that these areas have a similar tone to other water areas on the same sheet.
  3. Imagery on the final photomap shall be screened using a 133 line magenta contact screen.
  4. Mosaic joins shall be as inconspicuous as possible. There shall be no gaps or double images exceeding 1.0 mm in the assembly.
  5. There shall be no noticeable exposure patches detracting from photographic detail.

Linemaps

  1. Features and feature symbols on linemaps will conform, insofar as possible, with the Topographic Data Base Standards and Specifications, Second Edition, 1991, or later version, available from the Centre for Topographic Information, Sherbrooke, Quebec.

Approvals and Certifications

  1. The following statement shall be added to the map:
    "Prepared under the supervision of (name of surveyor C. L. S.)"
  2. The Surveyor General (or a person designated by the Surveyor General to approve such plans) will approve a base map if it conforms with this Chapter and the specific survey instructions. Base maps are filed in the regional records.

Returns

  1. The returns for basemapping shall include:
    1. a mapping report which includes:
      1. the scale and library numbers of the photographs used in the compilation;
      2. a list of models compiled;
      3. a description of instruments used and configuration; and
      4. a description of all occurrences of unresolvable parallax;
    2. for linemapping, two positives of the map on double matte stable based film, right reading emulsion down, of a thickness between 0.10 mm (0.004 in) and 0.18 mm (0.007 in), or as specified in the specific survey instructions;
    3. for photomapping, two halftone positives on the same type of film and of the same thickness as specified for line mapping in subparagraph (b) above; and
    4. all associated working material such as scribe sheets, manuscripts, master surrounds, lists of coordinates and/ or elevations used, and model set-up diagrams showing both the vertical and horizontal disparities with all set-up points used in the model.