5.4　Ground Feature Surveying and Mapping

5.4.1　Survey control points shall be denoted with the symbols specified in GB/T20257.1，Cartographic Symbols for National Fundamental Scale Maps-Part 1:Specifications for Cartographic Symbols-1:500，1:1000，and 1:2000 Topographic Maps and GB/T20257.2，Cartographic Symbols for National Fundamental Scale Maps-Part 2:Specifications for Cartographic Symbols-1:5000 and 1:10000 Topographic Maps.Elevation notes of vertical control points shall be rounded as required for accuracy rating.Horizontal coordinates of leveling points shall be determined against the main ground features and rounded to millimeter.All monumented mapping control points shall each be marked on map，and those nonmonumented ones may be marked where appropriate.

5.4.2　Water area surveying and mapping shall comply with the following requirements:

1　Rivers，lakes，sea，wells，springs，reservoirs，ponds，trenches and other water conservancy facilities shall be actually surveyed，with their designations（if any）noted on map.

2　Edges of rivers，rivulets，lakes and reservoirs should be determined based on the water level at the time of surveying.Where the distance between water edge and scarp line projected on map is less than 1mm，scarp lines shall be drawn in lieu of water edges.Water areas in flat areas shall be bounded by scarp or sloop lines rather than water edges on map，whereas reservoirs and ponds should be bounded by water edges.Trenches wider than 1mm on map shall be indicated with dual lines，and those narrower than 1mm shall be indicated by single lines and noted with symbols of flow directions.

3　Upper edges at inner side of trenches shall be mapped.Any earth embankments of 0.5m high above ground shall be mapped.

4　Coastlines should be surveyed based on mean high water.Dry shores shall be indicated with appropriate symbols or notes on map.

5　Underwater topography shall be generally described by contours，or may be otherwise noted with elevations where necessary.Seasonal rivers shall be noted with riverbed elevations；ponds shall be noted with top and bottom elevations；trenches shall be noted with bottom elevations and water depths；springs and wells shall be indicated with elevations of spring outlet and well curb，and noted with depth from well curb to water surface；and embankments and dams shall be noted with top and toe elevations.

5.4.3　Residential areas and facilities shall be surveyed and mapped in accordance with the following:

1　Various kinds of buildings or structures and the main ancillary facilities shall be mapped.Building outlines shall be bounded by projections of drip edges on ground；colonnades shall be bounded by horizontal projections of peripheral lines；eave galleries shall be bounded by projections of peripheral lines；overhead passageways shall be bounded by horizontal projections of peripheral lines；porches shall be bounded by peripheries of columns or enclosures；porches with independent columns shall be bounded by projections of top covers；overhung corridors shall be bounded by projections of peripheral lines；balconies shall be bounded by projections of bottom slabs；gate piers shall be bounded by pier peripheries；door tops shall be bounded by the projections of top slabs；exterior stairs and steps shall be bounded by horizontal projections of peripheral lines；for inverted pyramid buildings，their peripheries coming contact with ground shall be indicated by solid lines，and their projections of peripheries over ground be indicated by dotted lines.These principles shall be combined appropriately according to the mapping scales or on an as-needed basis.Any concavity or convexity on outline of building or structure less than 0.5mm on maps may be directly connected with line.Any roughly built hut or cabin smaller than 16mm2 on map may be omitted.Temporary moveable houses，residential camps and material storing sheds erected during construction may be neglected on maps.Residential areas，governmental institutions，and educational occupancies shall be noted with names（if any）.

2　Total stories of buildings shall include both aboveground and underground stories.Any semibasement with daylighting windows above grade surface shall be considered as a storey if the storey height indoors is more than 2.2m.Structures affiliated with building roofs，such as staircase，elevator machine room，water tank house and decorative towers，shall be considered as a storey if the storey height is not less than 2.8m.For duplex and mezzanine apartments，their storeys shall be calculated as the actually occupied number of storeys.Single-storey buildings，such as detached garages，power distribution room，water pump houses，and refuse bins shall be calculated as one storey.Single-storey houses shall only be noted with structure classification；overhung houses shall be noted with the storeys they span；houses in buildings and broken houses shall not be noted with number of storeys；and basements and septic tanks may be mapped on an as-needed basis.

3　Walls and fences shall be noted clearly with classifications and maintained or omitted as appropriate.Walls，fences and railings may be maintained or omitted according to their duration and importance.

5.4.4　Transportation facilities shall be surveyed and mapped in accordance with the following:

1　Classifications and levels of overland roads，ancillary structures and their relationship with the roads，road intersections，relationships between roads and other elements，river or maritime transportation navigation signs，navigation status of rivers，intersections between roads and rivers，and toll stations shall be faithfully reflected on map.Traffic lights，speed detection stations，and camera stations may be mapped as required.

2　Elevations shall be noted at top of railway rail，road crossing points，highway middles，bridge surfaces and slope changes.Elevations of gentle sloped roads shall be noted at an interval of 50mm to 100mm.

3　Highways and other two-lane roads shall be mapped based on actual widths.In addition，technical levels of highways，serial numbers of national highways，and pavement material of highways shall be noted on map.Positions where pavement material varies shall be separated with dot lines.Running directions of main highways shall be given.

4　Where railway intersects highway or any other kind of roads at the same height，the road symbols should be interrupted to maintain the continuousness of railway symbols.Where they intersect at different heights，appropriate bridge symbols shall be provided.

5　Road embankments and cuttings shall be bounded based on their actual widths，and noted with slopes and toe elevations as appropriate.Slopes with widths less than 2mm on map may be denoted by scarps.

6　Where a road crosses a residential area，the road symbol should not be interrupted but shall be mapped faithfully.

7　Bridges shall be mapped based on the surveyed positions of bridge head，body and pier，and shall be noted with structure classifications on map.Docks shall be mapped to reflect their actual outlines，and shall be noted with dock names（if any）or just noted with"Dock".Buildings on docks shall be surveyed，and denoted by symbols on map.

5.4.5　Lines shall be surveyed and mapped in accordance with the following requirements:

1　For the purpose of 5.4.5，lines shall include varieties of pipes，power lines and communication lines.

2　Permanent power lines，communications lines，substations，and transformers on poles shall all be faithfully indicated on map.Power poles and towers shall be mapped based on their surveyed positions，but may be omitted as appropriate where lines concentrate.In dense building areas，connections of power lines and communication lines may be omitted，but the connection directions shall be provided.Temporary communication lines，broadcast lines，street light lines，light box lines，and traffic light lines may be omitted as appropriate.Where multiple lines are laid on the same pole or tower，only the main lines require indication，but all lines on map shall run continuously and dawn distinguishingly.Transmission lines with 35kV or higher voltage level shall be noted with line designations，voltage levels，and tower numbers.

3　Turns of aboveground lines shall be faithfully reflected on map.Where supports of straight lines and accessory facilities are densely arranged，such turns may be omitted as appropriate，but each line shall be noted with line types.Underground manholes shall be faithfully mapped and noted.Fire protection facilities shall be faithfully mapped.Valves may be partially indicated as required.

5.4.6　Vegetations shall be mapped in accordance with the following requirements:

1　Topographic maps shall accurately reflect the species and distribution of vegetations，and the farmlands on which different crops are cultivated in different seasons.The main summer crops shall be considered as the mapping basis.Large-area vegetations may only be indicated with notes if they are readily identified.

2　Farmlands，garden plots and woodlands shall be mapped in scale，bounded with property lines，and noted with appropriate symbols.Where a property line coincides with a linear feature，the latter shall prevail.Independent trees that are worth reservation or have orientational significance shall be indicated on map.

3　Vegetations small than 3cm2 on map may be omitted regardless of species.

5.4.7　Industrial/mining buildings or structures and the associated facilities shall be mapped in accordance with the following requirements:

1　Open mining areas shall be mapped in scale to faithfully reflect their coverage.Industrial/mining buildings or structures and the associated facilities shall be mapped to accurately indicate their positions，shapes，nature and features.

2　Industrial/mining buildings or structures and the associated facilities requiring mapping in scale shall be mapped based on their surveyed outlines and noted with designated symbols or the required proportional cartographic symbols on map；for those not requiring mapping in scale，they shall be surveyed as point or linear features and denoted by non-proportional symbols.

3　Large nameplates and large pole billboards shall be faithfully indicated on map.Street，gardens，residential areas，and kindergartens equipped with recreational facilities shall be mapped based on their surveyed boundaries.Detached phonebooths and floor-mounted fixed mailboxes in public occupancies shall be surveyed and indicated on map.

4　Simple，temporary and low glasshouses，vegetable vaults，and greenhouses may be omitted on map.Graveyard should be noted with the number of graves.For large graveyards，property lines shall be surveyed for mapping.Positions of obvious independent graves shall be indicated on map.