Presenting metric measured drawing

Line weights make a big difference to the readability of drawings. By emphasising opening edges depth in the view is apparent and architectural form is evident as space and volume. Sections tend to reveal the value of lineweights as queues for depth perception:

St-Georges-E&-W-SECTION_01-Greyscale_detal

line weights determine open edges and recessive planes:

Lineweights for 1:50. CAD seems to have an ‘all or nothing’ approach to displaying line weights, they only seem to thicken up at the heavy end of the option:

‘Default’ seems to be about .25 at 1:50 scale, it’s best to avoid default as a line weight as it doesn’t mix with set sizes well. Opening edges are heaver than surface ones, near lines are heavier than far. Only 4 weights are used :

  • .35 for the cut lines,
  • .25 for opening edges,
  • .13 for most surface lines and
  • .09 for the monument moudings.

Greyscales. For digital presentation (jpeg on un-sized screens) I have matched the line weights to index grey tones, only the heaviest lines (.35 & .25) use black (7) the remainder are

  • 7 for heaviest lines only
  • 8 for near .25 lines
  • 9 for remote .25 lines
  • 252 for .09 lines
  • 254 for remote .09 lines

Busy line work needs light lines to avoid merging into a mass of ink at plot size.

In the above  (shown here at roughly 1:50 scale presentation) the brickwork is in .09 line weight with index colour 252, the banister and railings are edged in .13 in index colour 9.

The lightest (255) grey tone has little use as, being almost white, it is easily lost.

PDF generation does its own thing with line weights, this screen grab (above) is as viewed over size, the relative line thicknesses are retained but the absolute values are lost.

Basic rule. Using line weights has a big impact on the readability of drawings, the convention is simple: heavy lines show objects that are cut through, the next heaviest shows the outline ‘against the sky’ of openings and line weights recede with distance from the plane of projection.

A hierarchy of lines. The nearest lines are darker than the farthest, lines seen through are heavier than those we don’t.

B

 

About billboyheritagesurvey

Heritage worker
Gallery | This entry was posted in Significance, Survey Practice and tagged , , , , , . Bookmark the permalink.

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