📄 第一章 计算机图形学和图形系统基本知识.htm
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name=4>1.</A></FONT></SPAN><A name=4><FONT size=5><SPAN
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style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">计算机硬件简介</SPAN></FONT></A></FONT></H2>
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face=楷体_GB2312 size=4><B>一、常用的图形输入设备</B></FONT></SPAN></H2>
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face=楷体_GB2312 size=4>1．向量型图形输入设备
它采取跟踪轨迹，记录坐标点的方法输入图形。主要输入的数据形式为直线或折线构成的图形构成的图形学数据。常用的向量型图形输入设备有数字化板、鼠标嚣、光笔等。<BR>2．光栅扫描型图形输入设备
它采取逐行扫描，按一定密度采样的方式输入图形。主要的输入数据形式为一幅由亮度值构成的象素矩阵――图象（Image）。这类设备常采用自动扫描输入方式，因此输入迅速方便。但是，它所获得的图象数据必须被转换为图形（Graphics）数据，才能被CAD过程和各子系统所使用。这种转换，是一种图形识别的过程。最近，这方面的研究正在逐步达到实用阶段。常用的光栅扫描型图形输入设备有扫描仪和摄象机。<BR></FONT></SPAN></P>
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</SPAN></FONT><SPAN
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face=楷体_GB2312 size=4>从功能上可分为六类：</FONT></SPAN></P>
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size=4><SPAN lang=EN-US><FONT face=楷体_GB2312>1</FONT></SPAN><FONT
face=楷体_GB2312><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">）点坐标即定位；</SPAN></FONT></FONT></P>
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size=4><SPAN lang=EN-US><FONT face=楷体_GB2312>2</FONT></SPAN><FONT
face=楷体_GB2312><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">）一系列点的坐标即笔划；</SPAN></FONT></FONT></P>
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size=4><SPAN lang=EN-US><FONT face=楷体_GB2312>3</FONT></SPAN><FONT
face=楷体_GB2312><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">）数值；</SPAN></FONT></FONT></P>
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size=4><SPAN lang=EN-US><FONT face=楷体_GB2312>4</FONT></SPAN><FONT
face=楷体_GB2312><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">）选择；</SPAN></FONT></FONT></P>
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size=4><SPAN lang=EN-US><FONT face=楷体_GB2312>5</FONT></SPAN><FONT
face=楷体_GB2312><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">）图形识别；</SPAN></FONT></FONT></P>
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size=4><SPAN lang=EN-US><FONT face=楷体_GB2312>6</FONT></SPAN><FONT
face=楷体_GB2312><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">）字符串；</SPAN></FONT></FONT></P>
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face=楷体_GB2312 size=4><![if !supportLists]><SPAN lang=EN-US>1、<SPAN
style="FONT: 7pt 'Times New Roman'"> </SPAN></SPAN><![endif]><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">键盘</SPAN></FONT></P>
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face=楷体_GB2312 size=4> 有</FONT></SPAN><FONT face=楷体_GB2312
size=4><SPAN lang=EN-US>ASCII</SPAN><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">编码键、命令控制键和功能键，可实现图形操作的某一特定功能；</SPAN></FONT></P>
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face=楷体_GB2312 size=4><![if !supportLists]><SPAN lang=EN-US>2、<SPAN
style="FONT: 7pt 'Times New Roman'"> </SPAN></SPAN><![endif]><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">鼠标</SPAN></FONT></P>
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鼠标器是一种手持滚动设备，状如一个方盒，面上有2-4个开关，下面是两个互相垂直的轮子，或是一个球。当轮子或球滚动时，带动两个角度->数字转换装置，产生出滚动距离的x，y移动值。开关则用于位置的选择。鼠标器的一个重要特征是：只有当轮子滚动时才会产生和值变化。把鼠标器从一个位置拣起放到另一个位置，如果没有轮子的滚动，则不会输入任何信息。即鼠标器只能输入轮子的滚动值，而不能像数字化板那样输入位置值。因此，鼠标器不能用来输入图纸，而主要用于指挥屏幕上的光标。鼠标器价格便宜操作方便，是目前在图形交互上使用最广泛的图形输入设备。<BR></FONT></SPAN><FONT
face=楷体_GB2312 size=4><![if !supportLists]><SPAN lang=EN-US>1）<SPAN
style="FONT: 7pt 'Times New Roman'"> </SPAN></SPAN><![endif]><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">光电式鼠标</SPAN></FONT></P>
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利用发光二极管与光敏晶体管来测量位移：二者的夹角使二极管发光，经鼠标板反射至光敏晶体管，由于鼠标板均匀间隔的网格使反射光强弱不同，其变化转化为表示位移的脉冲；</FONT></SPAN></P>
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face=楷体_GB2312 size=4><![if !supportLists]><SPAN lang=EN-US>2）<SPAN
style="FONT: 7pt 'Times New Roman'"> </SPAN></SPAN><![endif]><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">机械式鼠标</SPAN></FONT></P>
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face=楷体_GB2312 size=4> 内有三个滚轴：空轴，</FONT></SPAN><FONT
face=楷体_GB2312 size=4><SPAN lang=EN-US>X</SPAN></FONT><FONT face=楷体_GB2312
size=4><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">向滚轴，</SPAN><SPAN
lang=EN-US>Y</SPAN><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">向滚轴，一个滚球；</SPAN><SPAN
lang=EN-US>X</SPAN><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">向、</SPAN><SPAN
lang=EN-US>Y</SPAN><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">向滚轴带动译码轮，译码轮位于两传感器之间且有一圈小孔，二极管发向光敏晶体管的光因被阻断产生位移的脉冲，而两脉冲成</SPAN><SPAN
lang=EN-US>90</SPAN><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">度</SPAN></FONT><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><FONT
face=楷体_GB2312 size=4>；</FONT></SPAN></P>
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face=楷体_GB2312 size=4><![if !supportLists]><SPAN lang=EN-US>3、<SPAN
style="FONT: 7pt 'Times New Roman'"> </SPAN></SPAN><![endif]><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">坐标数字化仪</SPAN></FONT><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><FONT
face=楷体_GB2312 size=4>:</FONT></SPAN></P>
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<SPAN
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size=4>数字化仪由一块平板和一个探头组成。它按工作原理的不同而分为电磁式的、超声波式的、磁致伸缩的、机械式的等等多种。<BR></FONT></SPAN><FONT
face=楷体_GB2312 size=4><SPAN lang=EN-US>1）<SPAN
style="FONT: 7pt 'Times New Roman'"> </SPAN></SPAN><SPAN
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">机械式坐标数字化仪</SPAN></FONT>
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height=144 src="第一章 计算机图形学和图形系统基本知识.files/image002.jpg" width=214
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