01 Data Capture Techniques Flashcards
What equipment would you take with you on a measured survey?
- Laser measure
- Tape measure
- Trundle wheel
- Pad and pen
- Tablet computer
- Binoculars
- Camera
- PPE
What are the limitations of a laser measure?
- Always contains a margin of error (usually +/-2mm but will be less accurate over longer distances)
- Care needed to ensure distance is perpendicular to surface
- Requires regular calibration to ensure accuracy
- May not work in bright light/daylight
- Requires batteries
- Potential hazard in use of laser
What are the limitations of a tape measure?
- Cumbersome over long distances
- Time consuming
- May require more than one person to ensure accuracy over long distances
- May expand in warm temperatures, losing accuracy
What are the limitations of a trundle wheel?
- Loses accuracy on rough terrain (due to wheel slippage and bouncing) and on soft/muddy surfaces (can affect the rolling of the wheel)
- Measures distance along a surface, not necessarily horizontal distance
- Obstacles in the way of its path may need to be accounted for separately using other measuring equipment
How would you carry out a measured survey on a property, including the checks you would put in place on your measurements.
- Methodical approach - room by room, clearly labelling each along the way
- Sketch the outline shape of each room including columns/reveals/staircases etc. (if using paper, usually draw one room per page with a datum point to the previous and next room)
- Start at a recognised base point and take key dims proceeding clockwise around the room
- Use laser measure, ensuring equipment is perpendicular to surface (use integrated spirit level if available or keep device flush with straight surface)
- Take an average of multiple measurements to improve accuracy
- Take measurements from different points along a surface as well as diagonals to determine if room is ‘out of square’
- Use tape measure for shorter distances or where no surface is available for the laser (e.g. width of a chimney breast)
- Use a tape and take ‘running dims’ as a cross-check
- Include all openings (doors, windows etc.) and any fixed furniture if required
- Depending on level of detail, may need sill/head heights, architraves, skirting boards, door thicknesses etc.
- Record floor to ceiling height if necessary
- Take external dimensions as a cross-check
If you were given drawings and specification to measure the concrete frame for a bill of quantities, what are the main checks you would undertake before you started measuring?
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Explain the process you go through when measuring an element of a building for a BQ.
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When measuring an element of a building for a BQ, how would you interact with the surveyors measuring other elements?
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Pick an element of a building that you have had to measure in detail and set out a typical ‘to-take’ list for that element?
Window:
- Structural opening width
- Floor to sill height
- Sill thickness
- Sill to window head
- Window reveal depth
- Number and size of panes
- Transom and mullion widths
- Distance from adjacent surface to determine its position
How would you go about measuring an irregular shape?
- Make a sketch of the shape
- Break it down into smaller shapes that are easy to measure (e.g. squares and triangles)
- Use Pythagoras theorem and trigonometry if required
- Take as many measurements as possible from different perspectives (e.g. from different base points, internally/externally etc.)
- May need to use specialist measuring equipment if complex (e.g. laser scanning)
What is a theodolite and when might it be used?
A precision instrument consisting of a moveable telescope mounted within two perpendicular axes used for measuring angles in horizontal and vertical planes
What is a total station?
An electronic/optical instrument consisting of an electronic theodolite and electronic distance meter (EDM) to measure angles and distances (used for topographic surveying or producing elevation plans)
How is a level used to establish a grid of levels?
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What is laser scanning?
A method of collecting surface data using a laser scanner which captures precise distances of densely-scanned points at rapid speeds used to generate 3D imagery (aka point cloud survey)
