9. What to check in the terrain

freemapper saves you drawing the base, not the walk through the terrain. Check above all:

• Buildings:
  • Are outline and passages right?
  • Are new buildings missing, or demolished ones still there?
  • Each building's data currency is in its object tags.
• Paved areas (sprint): in Saxony, street areas include the grass and tree strips at their edges. In Berlin freemapper cuts out the surveyed green strips (chapter 13); tree pits and green that the street survey does not know stay inside. In both states squares are only candidates.
• Canopies and passages: in every state except Saxony and Saxony-Anhalt, canopies and carports from ALKIS are map objects (522), and building passages and arcades are candidates (chapter 13). Are the canopies still there? Is a passage open, or does it have a gate?
• Fences, walls, hedges: they come from OSM and the nDSM, in Berlin also from ALKIS and the street survey, in Brandenburg and Bremen also from the full ALKIS. Can they be crossed? Are there gates?
• Out-of-bounds areas: private grounds, allotment gardens, railway land, and on schoolyard maps everything outside the school grounds.
• Berlin (chapter 13):
  • Canopies and carports from ALKIS are map objects (522). Are they still there? Where a canopy meets a building, freemapper cuts it at the wall. This can leave narrow slivers.
  • Building passages and arcades are only candidates. Is the passage open, or does it have a gate?
  • Stairs: the walking direction comes from the terrain model. If a stair rises less than 0.3 m in it, freemapper guesses. A stair at a building or monument leads up to it, any other one runs across its short side. These stairs carry the tag freemapper:direction=guessed. Check them first. Short stairs under about 2 m often look flat in the terrain model at 1 m resolution.
  • Wide stairs such as stadium stands come as several parallel 532.9 lines, one symbol width plus 0.15 mm apart (the norm's minimum gap), tagged freemapper:size=wide. Keep a few, or draw an area.
  • Walls: where ALKIS has both edges and the centre line of a wall, the candidates show two or three parallel 515 lines. Take one and delete the others. ALKIS has no height. Whether a wall can be crossed is for you to decide in the terrain.
  • Trees: species and crown are in the tag freemapper:baum, e.g. Tilia cordata, Krone 12 m. The tree cadastre can be older than the trees on the ground. Trees on school grounds and private land are mostly not in it.
  • Street survey: it was recorded from 2014 to 2016, so it is about ten years old. Streets rebuilt since then are in it as they were. Check curbs, railings, walls, furniture and green strips in the terrain. If a green strip that freemapper cut out has been paved since, the paved area has a white spot. Fill it from the orthophoto.
  • Guessed survey dates: candidates with freemapper:currency_guessed=yes and paved areas with freemapper:cut_currency_guessed=yes have no readable survey date. freemapper then sets 2014-01-01. Check these places first.
  • Railings, traffic barriers and crash barriers are 518 candidates (impassable). Where people can climb over them, use 516.
  • Buildings: a Berlin building's data currency is its footprint date from the building heights of 2022, often years before the fetch. Buildings added since 2022 have no date.
• Banks and bridges:
  • The cadastre area of a body of water can include the bank slope. Move the bank line to the water's edge, using the orthophoto.
  • The bank line runs across bridges. Cut it there by hand.
  • The cadastre often records a road bridge as road area. The water then ends at the bridge, and a bank line runs across the river. Delete that line in OOM and extend the water area under the bridge.
  • Where two water areas almost meet, such as those of two states at the border in mid-Rhine, freemapper closes gaps under 0.5 m. A bank line in the middle of a river therefore stands for a wider gap in the cadastre. Check in the orthophoto whether there is land.
  • Water from the cadastre is always uncrossable (301), because the cadastre has no depth. Shallow water that you can wade through becomes a crossable body of water (302).
  • Water from OSM comes as candidates only. Are the pond and the fountain still there? Does the ditch carry water?
• Brandenburg (chapter 13):
  • The full ALKIS often records a wall as its two edges (Mauerkante, links and Mauerkante, rechts). Where both edges face each other, run nearly parallel and lie closer than 0.55 mm on paper (2.2 m at 1:4000), freemapper draws one 515 line in the middle. It carries freemapper:alkis=Mauer (Mauerkanten gepaart) and names the other edge in freemapper:also. Thicker walls stay two lines: keep one, or draw the wall as an area. A gate in only one edge also breaks the middle line, so check gaps in the orthophoto.
  • The data currency of these candidates is the date the object version entered the cadastre, not a survey date. A fence can have changed since.
  • Potsdam trees are all 418, because the city data has no crown size. Mark large trees as 417 yourself. Each tree carries its own survey date, some of them from 1993.
• Thinned points: where two point symbols would come closer on paper than the norm allows, freemapper keeps the larger one. The kept point names the others in freemapper:generalized. Rows of street trees stay single tree symbols. Where they stand closer than the symbols allow, some of them are dropped. Check the gaps in the terrain, and move symbols apart where both objects matter.
• Tree groups as areas: three or more trees form a group when they stand closer than 2.5 mm on paper (10 m at 1:4000) or their crowns come within 0.5 mm of each other. A row stays points, such as the trees of an avenue or a street, also with trees on both sides. Each tree of the group claims a circle of 5 m radius, or its crown if that is larger. If half of that lies on paving, the group becomes paved area with scattered trees (501.3), provided it takes in at least 9 trees. Otherwise it becomes forest (405) when the crowns cover at least half of the area, else open land with scattered trees (402). On the sprint map the white forest shows on the park's yellow or on the brown of the walkable area without an outline. On the schoolyard map, whose base is white, a forest that does not lie half on open land (401 to 404) gets a distinct vegetation boundary (416) as a dotted outline. Where the area ends at a building, water, an out-of-bounds area, paving or a path, this boundary is left out. freemapper cuts roads, squares, paved candidates and paths (505, 506, 507 at their width on paper) out of forest and 402, so that no area covers a path. Where a piece is then below the minimum size, its trees stay points. A strip only one row of trees wide falls out of the area and stays points. The area and its boundary carry freemapper:source=generalization and list the trees in freemapper:source_id. Their tag freemapper:generalized gives the number of trees and the crown cover. Large trees (417) stay points on a 402 area. Without a measured crown, freemapper assumes 12 m for 417 and 5 m for 418, which is usually too small for park trees. Compare the outline with the orthophoto. In the cadastre a park is park throughout: wooded parts without tree data stay yellow, draw them as 405 yourself.
• Overlapping walls, fences and hedges: where two of these lines run parallel and closer than their symbols may come on paper (half their widths plus 0.15 mm between two black lines, at least 1.5 m for two sources), the weaker line loses that stretch. The better source wins (register before ALKIS before street survey before OSM), and for one source the stronger symbol: wall 515 before fence 518 before hedge 410.1 before retaining wall 513.2. Two lines of one source with the same symbol stay, because they are two objects. A wall running parallel within 0.5 m of a building outline is dropped there, because the outline already draws it. Leftover pieces under 1 mm are dropped, and a line that ends at another stays whole. The winning line names the cut one in freemapper:also. A tree within 1 m of one of these lines is dropped, and the line names it in freemapper:generalized: in a hedge it belongs to the hedge, at a wall or fence its symbol covers the line. In Park Sanssouci the OSM retaining walls of the terraces give way to the ALKIS walls this way. Check on site which walls a runner can jump down (513.2), and move a real fence next to a wall aside instead of leaving it out.
• Hidden points in out-of-bounds areas: ISSprOM allows no feature in an out-of-bounds area (520) except very prominent ones. A point candidate inside a 520 candidate stays in the candidates, tagged freemapper:hidden=520, but the check print and the training map leave it out. On schoolyard maps this hides every point off the school grounds. If the area is not out of bounds after all, or a very large tree stands in it, take the point over from the candidates.
• Furniture and playground equipment: it comes from OSM, in Berlin on schoolyard maps also from the street survey and the lighting cadastre. It is often incomplete.
• Contours: small banks and steps show better in the hillshade, slope or local relief; the knoll and bank candidates point to them. The contours run through buildings, ways and paved areas, as ISSprOM 2019-2 (101) asks. They are broken only at stairs, at the small landform symbols (105, 109 to 112, 115; on forest maps not at the earth wall 105), below cliffs drawn and in water from the cadastre (ADR 0140).
• Fence ticks: a closed fence has them inside, as the norm wants. Otherwise they point to the olive green area beside the fence, away from a way along the fence, and to the park. With the same area on both sides freemapper takes the side where the ticks overdraw nothing.