V N G H I E N CLFU XAY DI/NG CHU'aNG TRJNH QUET MAU 3D
RESEARCH TO BUILD A 3D SCANNER PROGRAM
ThS. Nguyin Van Cdng
Trung tim Cdng nghe, Hpc viln Ky thuit Quan sU
TOM TAT
Bdi bdo trinh bay kit qud nghien cdu xdy dUng chUdng trinh quet mdu 3D. ChUdng trinh cd thedUdc Ung dung cho cdc thiit bi quit mdu trong linh vUc ky thudt ngUdc. ChUdng trinh dUde xdy dung trin cd sdphdn mem Processing. Nguyen ly hoat ddng cua chddng tnnh dUa tren tinh todn tga do 3D td nhdng bdc dnh 2D la nhdng hinh dnh cua vat thed nhdng gdc quay xdc dinh trUdc.
Tic khoa: Quet laser 3D; Ky thudt ngUdc; Phdn mem quit mdu.
ABSTRACT
The paper presents the results of the research to build a 3D scanner program. The program can be applied to a scanner equipment in the field of the reverse engineering. The program is built base on the Processing sojiware. The principle of operation of the program is calculate the 3D coordinates from 2D images, which is the images of the object at the predetermined angles.
Keywords: 3D laser scanner; reverse engineering; scanner software. "^
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NGHIEN Ctfu KHOA HOC
I.DATVANDE
Cdng nghe quet mau 3D mdi ra ddi trong khoang vai chuc nam trd lai diy va dang phat trien rat nhanh ehdng. Nhilu hang ldn trin t h l gidi lien tuc cho ra ddi nhiing thiet bi quit mau vdi dp chinh xae ngay cang cao, pham vi quit ngay cang ldn. O Viet Nam, van de ehe tao thilt bi quet man cdn rat mdi me va dang bat dau dUpc chii y tdi. Cd mdt sd nghien cUu cua cae trUdng dai hpc dUde tiln hanh nham che t^d ra cac thilt bi quit mlu. Nam 2010, t i e gia Nguyen Van Vinh, Vii Hoang Tuan, Nguyin DUdng Hiing, DUdng DUc Hieu [1] da cdng bd kit qua nghiin cUu che tao thiet hi quet dUa trin nguyen ly dau phat laser va webcam chuyen dpng tinh tien theo phUdng thang ddng d l quit tiing lat cat ngang ciia vat the. Ket hdp vit the chuyin ddng quay trdn de dam bao quet dupe toan bd vat the. Diy cd the coi la cdng bd dau tien cua Viet Nam ve van de che tao thiet hi quit mau. Nam 2013, tic gia Nguyen Van Tudng ciia TrUdng Dai hpc Nha Trang da ifng dung phan mem DAVID Laserscanner kit hdp vdi viec ttf che tao he thdng cd khi de c h i tad thiet hi quit m i u 3D. Hifdng tilp can nay khdng dam bao yiu td Iim chu edng nghe.
Dau nam 2014, tac gia Nguyin Thanh Nam ciia Trudng Dai hpe Bach khoa TP.Hd Chi Minh da cdng bd kit qua nghiin cdu che tao thiet hi quit 3D dUa trin nguyen ly gidng vdi nghien eUu ciia nhdm tac gia Nguyen Yan Vinh da ndi d tren. NhU v^y, ed t h l thay rang, viec nghiin cUu c h i tao cac thiet hi quit laser d Viet Nam hiln nay la rat mdi me, sd lUdng cae nghien eUu ve van de nay la rat it. Dilu nay ehi ra rang, van d l nghiin cUu de ttf che tad cac thiet bi quet m i u 3D la can thiet. Dae bilt can chii trpng vao nghiin cdu xiy dUng phan mem xif ly eho cac thiet hi nay, vi van de p h i n m i m la mdt van d l khd, giai quylt dUpc van de phan m i m se dam bao yiu td lam chu hoan tdan ve cdng nghe. Bai
bad trinh bay kit qua nghiin cdu xay dUng mdt chUdng trinh xif ly dii lieu cho cac thiet hi quet mau 3D vdi tinh nang thu t h i p dUpc t i p hpp tpa dp cae diem tren be mat eua mot vat the can quet.
2. NGUYfiN LY HOAT D 6 N G CUA CHI/ONG TRINH QUET MAU 3D
ChUdng trinh quet mau 3D hdat ddng theo nguyen ly sau: Khi ehieu tia laser lln vat the sl de lai tren be mat vat the mdt vet sang (hinh 1).
Hinh 1: Quit laser
Webcam chup anh vit the cd vet sang ciia tia laser t r i n b l mat dd. ChUdng trinh se dUa vao dp sang ciia vet laser de tim ra tpa dp trin anh 2D cua dilm dang dUdc ehilu sang (hinh 2), tU do tiep tue tinh toan ra tpa dp cua dilm dd trong khdng gian 3D (hinh 3).
r
L Hinh 2: Anh chup vd toa do 2D
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3.2. Xay dilng childng trinh
Tren ed sd thuit toan chUdng trinh nhU da trinh hay, ta sif dung phan m i m Processing [3] d l viet cae lenh thilc h i l n cac nhilm vu theo nhu thuat toan.
Hinh 3: Toa dd 3D cua diem Kit qua xii li chinh la tap hpp tpa dp x, y, z eua eac diem (edn gpi la dam may diem - point cloud) se dUdc lUu vao mdt file dudi dinh dang asc la dinh d^ng ma cac phan mem thilt k l ngUde d i u cd the dpe dUde.
3. X A Y DI/NG CHU'ONG TRINH Mue dich ciia chUPng trinh la thdng qua vile p h i n tieh hinh anh 2D cua vit la- ser tren be mat viit the d l tinh toan ra tpa dp thilc trong khdng gian 3D ciia cac diem sang.
ChUdng trinh dupe xiy dUng trin phan mem Prdcessing ket hdp thU viln GSVideo.
3.1. Xay dUng thu^t toan
LUu do thuat toan cua ehUdng trinh nhu hinh dddi:
3.2.1. Xd lianh 2D
Sau khi da ed dUpc anh chup 2D cua mau vat vdi vet sang laser mau dd trin dd.
ChUdng trinh se p h i n tich i n h nay, can cU vad dp xam ciia tUng diem anh de chUdng trinh xtf Ii anh truy xuat ra vi tri cua vet laser trin be mat mau vit [4]. Giii mau phan bo tU 0 den 255, trong do mUc 0 tUdng Ung vdi mau den va mUc 255tUdng dng vdi man trang:
Qua trinh xU li anh thUe hiln theo tdng hang, tren mdi hang se so sanh ve dp xam eua tdng diem i n h de lpc ra mdt dilm duy nhit ed gii tri dp xam Idn nhat. Dilm nay sl dUpe gan cho gia tri dp xam la 255 tUdng Ung vdi mau trang, tat ea cae diem khac tren cung hang sl bi gan vl mau den. Doan chUdng trinh xif li anh 2D dUdc t h l hiln trong hinh 4.
Bat dau Chup anh
1
i
Xa li anh Tinh toan tpa do 3D
1
I
Tao file luu tru dam may 1 K^t thiic
1
Hmh 4: Doan chUdng trinh xd li dnh 2D 3.2.2. Tinh todn tga do 3D
D i u vao eua qua trinh tinh toan tpa dp 3D chinh la bdc anh den trang cd dddc d giai doan xif U anh 2D phia trUdc. Vdi moi diem mau trang, khoang each giCa nd va dUdng thang^
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NGHIEN Ctfu KHOA HOC
ddng ehinh gida anh chuih la gia tri khoang each b trong hinh 2.
b=((maxBrightPos-i-l-row*scan.width)-sean.
width/2)/pixel_tb;
6 day, can chu y la tham so pixel_tb la sd diem anh tren 1mm kich thudc thUe. Tham sd nay cd dUde sau khi tiln hanh hilu ehuan cho phin mem.
Tham khao hinh 2 ta cd: r=b/sin(alpha);
Tham khao hinh 3 ta cd: Xo=r * eos(phi);
Yo=r " sin(phi); Zo=row/pixeI_tb;
Doan chUdng trinh tinh t d i n tpa dp 3D nhu trong hinh 5.
b-((maxBH|hTPoa'»l- r - b / s l ( i { i l p h » ) ; Ko-r • eos(phi)[ / / i Yo-r . »in{ph4)[
Zo-row/plxel.tb;
«ridib)-»cin.iiri(fth/2)/pHKel_tbi
Hmh 5: Doan chUting trinh tinh todn tga do 3D Nhu viy, vdi moi mdt diem mau trang t r i n anh ta se tinh ra mdt bd 3 tpa dp (Xo, Yo, Zo) eua diem mau trang dd.
3.3. Chay k i l m nghiem chUdng trinh Sau khi hoan thiln dUde ehUdng trinh, tae gia da tiln h i n h chay kiem nghiem chUdng trinh. Muc dich ciia vile Idem nghiim la de danh gia kha nang hdat ddng ciia chUdng trinh ve eac mat: Kha nang thu thap dd lieu tpa dd 3D, dp chinh xac ve hinh dang hinh hpc va dp ehinh xae kich thUdc.
21.7G
2
• 4 0 . 8 6 1
• 5 7 . 8
Hinh 6: Bdn ve mdu vdt Vile Idem nghiim dUdc thUe hien thdng qua vile q u i t mdt vit the hinh tru b i c cd ldch thude nhu hinh 6. Tim tru dddc hd tri triing vdi giao dilm ciia phUdng ehilu laser va quang tam cua Webcam. Khi bd tri nhU vay, neu cho m i u vit quay trdn thi vi tri vet laser se khdng thay doi. Do dd, ta ed the d l m i u vit ddng yIn va dung tham sd de thiet lap chuyen ddng quay trdn gia dinh ciia mau vat, lam nhU t h l vdi muc dich thu dupe tpa dp 3D ciia ca mau vat.
I
Hinh 7; Mdt dnh chup mdu vdt, hinh dnh sau xd li 2D vd tga do 3DVdi phUdng phap thUc nghiem nhU vay, ta tiln hanh quit mau va thu dupc nhflng ket qua nhu the hien trong hinh 7.
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3 J «
1 " 1 ^
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1
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1
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Kit qua quet m i u dUde lUu trfl trong file scan.asc, sd dung mpt phan m i m thiet ke ngUdc ta ed t h l quan sat va p h i n tieh kit qua.
VI mat hinh dang hinh hpe, cd the thay rang dfl lieu 3D thu thip dUpc phan anh kha chinh xae tUdng quan hinh dang hinh hpe. DUdng sinh cua cac doan tru deu kha thing. Kit qua kiem tra dp ehinh xae kich thude dUde t h l hien trong bang 1 va bang 2.
Hmh 8: Do kie'm kich thUdc
Bdng 1: Bdng kit qud kiim tra do chinh xdc kich thUde dUdng kinh mdi doan tru.
STT 1 2 3
Kt D a n h nghia 37.5 66.8 59.5
Kt Scan 37.654 67.000 59.580
Dp CX tiiang doi (%) 0.408 0.299 0.134
Do CX tuyet doi (mm) 0.154 0.200 0.080 Bdng 2: Bdng kit qud kiim tra do chinh xdc kich thUde chieu ddi mdi doan tru.
STT 1 2 3
Kt D a n h nghia 22.75 46.74 56.50
K t S c a n 22.745 46.500 56.450
Dd CX tiiang doi (%) 0.022 0.516 0.089
Do CX tuyet doi (mm) 0.005 0.240 0.050 4. KET LUAN
Vile nghiin cdu xay dUng phan m i m quit m i u 3D cung nhU thiet bi quit mau 3D la vile lam can thilt ddi vdi nUde ta. Nghiin cdu nay da xiy ddng dUdc mot ehUdng trinh quit mau 3D cd the dng dung chd thilt bi quet mau trong linh vdc thilt ke ngdde. Kit qua cua nghien cdu se gdp phan thuc day sd phit trien trong linh vUc c h i tao thiet hi q u i t mau 3D.
Nhflng k i t qua da dat dUdc trong nghien edu nay rat can dUdc t i l p tuc hoan thiln hdn v l mat chat lupng, d i e biet la can phai tien hanh kit hdp nghiin edu phat triln phan cdng di kem de cho ra nhflng thilt bi quit m i u hoan thiln. •
Ngiy n h i n bail 19/8/2014 Ngay phan biln: 20/9/2014 Tai lieu t h a m khao:
[1]. Nguyen Van Vinh, Vo Hoang Tuan, Nghien cdu vd chi tao mdy quit laser 3D theo dUdng, Hpi nghi Khoa hgc Ky thuat Do lUdng toan qudc lan thd V (2010).
[2]. Nguyin Van Tudng, Thiet ke vd cM tao thiit bi quit laser dting trong ky thuat ngUdc phue vu ddo tao, TrUdng Dai hpc Nha Trang (2013).
[3]. Learning Processing, Daniel Shiffman, Morgan Kaufmann (2008).
[4]. LUdng Manh Ba, Nguyin Thanh Thuy, Nhap mon xdly dnh sd, NXB. Khoa hoc va Ky thuit (2006).
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