Quantity takeoff software uses AI to read a project's drawings and aerial images, and produces the quantity takeoff in minutes. A quantity takeoff is the list of every item a design needs, and how much of each: the number of doors, the metres of wall, the square metres of floor tile. Estimators used to count these by hand from the drawings, which could take days for one building. The software is a part of construction estimating software.
How does a machine read a drawing? A drawing is an image of lines, symbols and text. The software uses computer vision, AI that has been trained on thousands of labelled drawings to recognise what is in an image. It finds each door symbol, each window, each wall and each room outline. It reads the scale from the title block, the box of details in the corner of each sheet. Then it measures lengths and areas in real units. For work outside a building, such as roofing or landscaping, the same method is used on photos taken from aircraft or satellites.
Say an interior contractor in Hyderabad is bidding to fit out four floors of an office building. The drawing set has 64 sheets. By hand, an estimator would need about three days to count everything. The software reads the set in 15 minutes. It finds 212 doors of four types, 3,900 metres of drywall partition and 7,450 square metres of floor. It splits the floor into carpet for the work areas and tiles for the toilets and pantries. It shows every item that it counted in colour on the drawings, so a person can check it.
The estimator then checks the result, sheet by sheet. Here the software has made two mistakes. It has counted 6 glass panels as doors, and it has missed a 40 square metre store room drawn on a separate detail sheet. She corrects both in about an hour, in the takeoff tool's own viewer or in PDF markup for construction. Her final count has 206 doors and 7,490 square metres of floor. The whole takeoff has taken under two hours instead of three days.
Why does this matter? A contractor wins only a few of the jobs it prices. When counting takes days, an estimator can price only a few jobs each month. When counting takes hours, the same estimator can price many more, and spend her time on the rates and the risks instead. The counting method itself is explained on the page on quantity takeoff. Counting from drawings matters most when there is no BIM model to read the quantities from, which is still common on smaller jobs in India.