1. Xa yuam kev:
qhov tseeb loj ntawm lub xeem thiab theoretically ntawm meej meej ntawm qhov txawv ntawm qhov lub npe hu ua qhov yuam kev ua.
Cov ua haujlwm uas tsis sib haum yog muab cais tawm raws li hauv qab no:
1. Txiav txim siab yuam kev 2. Hloov ua yuam kev 3. Qhov chaw yuam kev 4. Qhov teeb meem ntawm qhov teeb meem ntawm qhov teeb meem 5. Kev ua yuam kev
2.Yeej:
Kev kam lees yog hais txog qhov ntau ntawm qhov loj me, geometries, geometric positional kev sib raug zoo, thiab qhov tseem ceeb ntawm qhov chaw roughness. Kev tawm tsam raug siv los txwv qhov yuam kev.
Kev tawm tsam yog raug faib ua cov hauv qab no:
1. Pluag Tiv Thaiv 2. Ua Zoo Tsis Zoo 3. Txoj Haujlwm Kev Tiv Thaiv 4. Qhov Ncauj Txwv Tsis Taus
3. Txheej Txheem:
standardization yog hais txog kev tsim cov qauv thiab kev ua raws li cov qauv kev qhia ua cov ntsiab lus ntawm tag nrho cov txheej txheem ntawm kev ua ub no.