如何用PS创作一幅概念设计作品——风格特别，思路新颖。_CG世界-爱微帮
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点击上方蓝色字CG世界&关注CG阅读学习平台“&感知CG · 感触创意 · 感受艺术 · 感悟心灵&”————&WORLD_CG&————CG世界编译整理未经许可谢绝任何形式转载很久没推送图文了，大家都着急了吧？在这里说声抱歉，因为最近项目多，实在没有时间来整理。抱歉，抱歉。今天给大家送上一个大咖的概念设计过程教程。本来这个教程今年年初就想翻译了，结果一推再推，推到现在。希望大家喜欢！&Donglu是一位在游戏行业工作多年的高级概念艺术家。参与制作了很多大型游戏。&以下为Donglu叙述Pansking翻译整理通过这节课的制作流程，我会给大家展示在锁定最后的渲染设计之前如何挖掘一个缩略图和草图构思。在落笔和绘制之前计划好步骤是非常重要的。&一个概念艺术家所扮演的角色是给平台提供不同的视觉解决方案，不仅仅是生产一些优秀的渲染艺术作品集。因很多类型的数字艺术作品可以在网上看到，使得概念艺术和插画领域的界限变得越来越模糊，但两者之间其实有着非常大的区别。&我开始选择一个适当的图片，在这个基础上我快速的建立一些自定义的形体，生成一个比较大的构图范围。在游戏制作开发阶段，与艺术总监沟通早期的设计草图在整个过程中非常重要。&在这里，我将选择图形着色，揭示一些PS技术和工具。细节阶段，我将会在颜色草图的基础上整合图片纹理，然后借着机会解释一些基础的艺术理论。完成艺术作品之前，我使用了一点点技术，比如Chromatic&Aberration，Zoom&Blur和Sharpen&Filters。这些工具的使用将会覆盖我整个的制作流程。视频绘制过程，请点击底部蓝字“阅读原文”下载第一步图片收集积累个人的图像银行尤为重要。这不仅仅可以提供原始的素材可供你应用，而且这些照片的版权也属于你。我挑选出一些城市远景图片，我整理的是中国和美国中的一些城市，并且快速的浏览了下其中哪些元素可以用在我的概念中。&第二步提取我的目标形体有关形体和剪影轮廓我现在有一个很好的想法。我把我的图片参考拖拽到Photoshop中，提取我选择的形体。你可以使用你认为好用的任何一个选择工具，什么Color&Range，或者Lasso也或者Masking工具。通常我调整对比度，在自定义形体时那样可以产生更好的效果。&第三步创建自定义形体我使用通道范围选择我的形体，然后产生各种效果。我反选，按下键盘的M键，右键并选择Make&Work&Path。设置Tolerance值为0.5，然后点击Edit和选择Define&Custom&Shapes。我自定义的形体现在在Shape工具的下面。我重复以上步骤生成不同的建筑外形，以建立起我的城市远景轮廓。&第四步缩略草图在画布上我拖拽形体，快速的制作一些有趣的构图范围。当创建这些缩略图的时候，思考这些剪影，深度和灯光的方向至关重要。你知道这个过程是多么有趣和快速么？想象一下当你和艺术总监讨论你的视觉图像时，这些草图将会变成有价值的资产是多么的有意义。&第五步确定草图我休息了一小会，然后后退几步尽可能的思考我制作的东西。我选择一个最有潜力的，同时结合了其他缩略图的几个要素。然后确定了最后的草图，但是我决定调整些整体的形体，值和对比度，加入了一些亮度值比较高的广告牌。&第六部加入颜色利用Photoshop的Adjustments层，我铺设了第一个颜色。建筑周围我想是暖色的，人造灯光，在建筑的顶部融入一些淡淡冷色天空。&我创建了一个Hue/Saturation&Adjustment层，勾选Colorize，调整Hue滑动条。在遮罩层上我拖拽了一个渐变，以使暖色只影响图像的底部。我同样也创建了另一Color&Balance层和一个Hue/Saturation层，生成一个暗蓝色的背景。&第七步用基础笔刷着色我选择一个草图笔刷和引用了一些颜色噪波在着色区域。这就产生了一个讨人喜欢的，绘画的感觉。如果你没有自己自定义的笔刷，那么用默认的Charcoal笔刷也同样能达到很好的效果。第八步把自定义样本放置在一起个人颜色样品将会加快我的颜色选择。所以，我拾取了一些灯光参考，把尺寸大小减小到大概500像素宽，点击Filter&Gallery&Texture&Patchework。&我增大了方块的尺寸大小，并取消选择Depth选项。现在我可以从这些样品中拾取颜色，引用到我的场景中作为高饱和度的光源。&第九步图像整合我拽一些纹理图片，让场景看起来更为真实些，擦除图片中的一些无用元素。当我擦掉区域中的一些纹理时，一些抽象的形状变为可见了。这，有时候能给我一些新的想法。为达到不同的目的，我拖拽了一些不同的图像，如提取了一些有趣的前景形状或者提高了灯光。&&第十步制作高光在这里，我介绍一个快速制作高光的方法，用来产生错觉的细节。我使用一个硬笔刷，放置了一些不同的线，然后用一个纹理画笔将它们松散地清除，以产生随机的外观。注意，亮点必须是和光源一致的，所以想想你的照明光源。&第十一步场景角色这里，我加入一些随机设定的角色生成对比度，有助于我建立一个活生生的世界。你可以使用自定义的形状或自定义画笔技术来绘制不同的角色，例如平民、士兵或机器人。我把一大群人融入到图像中，并用一个机器人的轮廓与人类的比例进行对比。第十二步修整构图为了帮助把所有元素融合在一起，我用笔刷又作了一些额外的绘制工作。我经常用笔刷模仿传统工具，如油画和水彩。&这个阶段你可以通过简化的形体，或者增加颜色的方式。这里我使用ArtRage，因为它有一套完整的绘画工具，可以模仿传统绘画的感觉。&第十三步加入径向模糊返回到Photoshop，并加入一些微妙的径向模糊。这会给我的艺术场景一些运动感，和有助于混合纹理和笔刷的过度。&首先，在一个新层上合并一个图像，然后拾取Filter&Blur&Radial&blur，选择Zoom设置参数为10像素。我把Zoom层和Masking工具结合起来。在遮罩上我弄了个渐变，所以只有底部显现出来。&第十四步色差和锐化我用色差和锐化完成了我的场景。对于前者，我点击Filter&Lens&Correction，点击Custom&Tab并调整Chomatic&Aberration滑动条。然后我点击Filter&Sharpen&Unsharp&Mask,并调整Amount，Radius和Thresh设置。教程完毕下面我们一起来看看大师的一些其他精彩作品吧·&CG世界&·微信号：world_CG投 稿 · 商 务 合 作 · 意 见QQ-— — — — — — — —运营者微信：motionlight公众号只是个平台，朋友圈才是真爱想加入微信群也请加此号
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The panorama tools have a very flexible model to correct for typical geometrical lens errors. Even better, it can often even estimate the correction parameters directly from the images in a panorama.
There are a total of 6 parameters that have to do with lens correction.
First of all there is the lens
(FoV) - not exactly an error, but a parameter that determines the image perspective distortion.
The actual lens correction parameters a, b and c which are used to correct for ,
and even .
The lens shift parameters d and e that correct for the lens optical axis not being in the image center.
Two more parameters correct for image errors that are not induced by the lens but by a scanner or scanning camera for example. These are the shear parameters f and g.
is a physical property of the lens. Together with the effective sensor or film size and the focusing distance it approximates the image
(there are other factors that influence it). Caution: Cropping the image changes the Field of View. If you need to crop your source images for a panorama, crop them all to the same size!
The Field of View together with the lens projection (,
for swing lens cameras) determine the image . Perspective distortion is less with a smaller Field of View. See Helmut Dersch page
for details about different wide angle perspectives.
For perfect
camera optics, all you would need to know is the field of view.
Perfect results could be achieved by simply mapping pixels in the image to the tangent plane.
Real lenses deviate from this perfect tangent plane projection.
The deviations push and pull fixed points in the scene away from where they would have fallen.
Luckily, rather than arbitrary pushes and pulls, almost all deviations occur radially, towards or away from some common center, and luckily the deviation amount is almost the same at a given radius around that center. Hence a model that corrects for this deviation based on the radius gives pretty good results.
a, b and c parameters correspond to a third degree polynomial describing radial lens distortion:
refer to the normalized radius of an image pixel. The center point of this radius is where the optical axis hits the image - normally the image center.
Normalized means here that the largest circle that completely fits into an image is said to have radius=1.0 .
(In other words, radius=1.0 is half the smaller side of the image.) A perfect lens would have a=b=c=0.0 and d=1.0 which resolves into
Sometimes the above formula is written as
which is essentially the same.
Usual values for a, b and c are below 1.0, in most cases below 0.01. Too high values suggest that you chose a wrong lens type, f.e. fisheye instead of rectilinear or vice versa. This refers to the absolute values of course since a, b and c can be positive or negative (f.e. both 4.5 and -4.5 are considered too high values).
The fourth parameter (d) is only available in the Correct, Radial Shift filter of the Panorama Tools Plugins. It is calculated implicitly by
(used by PTOptimizer, PTStitcher and the GUIs) in order to keep the same image size:
Hence it is not available in the different GUI front-ends (you can see it in the PTOptimizer result script).
Unfortunately a different parameter also named d refers to image shift in PTStitcher and PTOptimizer scripts and the GUIs.
This sometimes causes confusion. (See more discussion below.)
This polynomial approach is never exact, but can give a pretty good approximation to the real behaviour of a given lens. If you need better correction you must use a distortion matrix, as used by Distortion Remove (see link below).
Unlike rectilinear lenses, fish-eye lenses do not follow the tangent-plane geometry, but instead have built-in distortions designed to achieve wide fields of view.
The radial lens distortion parameters are used the same way for rectilinear lenses and fisheye lenses, but they should never be used to attempt to remap a fisheye to a rectilinear image.
This is done by selecting the proper source and destination projection.
Fisheye geometry follows a rapidly-changing trigonometric function which can hardly be approximated by a third degree polynomial.
For fisheyes, the lens correction parameters correct for the deviation between a real lens and the .
Sometimes a lens and image sensor might not be centered with respect to each other. In this case the optical axis doesn't fall on the image center. This is particularly the case for scanned images where you never can say whether the film is centered on the scanner or not.
If the above lens correction algorithm is used on such images both lens correction and perspective correction work on the wrong center point. The lens shift parameters d (horizontal shift) and e (vertical shift) compensate for that problem. They contain values in pixel units which determine how far the center for radial correction is shifted outside the geometrical image center.
Image shear is not a
but nevertheless is part of the panotools lens correction model. It corrects for a distortion induced by scanners or scanning cameras that causes a rectangular image being sheared to the form of a parallelogram (one side of the images is shifted parallel to the opposite side)
a, b, c and FoV are physical properties of a lens/camera-combination at a given focus distance. If you always shoot at the same focus setting, f.e. infinity or the , then you can safely reuse the parameters.
At different focus settings, FoV will change noticeably, but usually it is fine to reuse a, b, and c even then.
There are a number of ways to determine the a, b, c and
parameters to calibrate a particular lens/camera combination:
Taking a single photograph of a subject containing straight lines, defining one or more sets of
(types t3, t4, etc.), and optimising for just a, b, c.
You need to set the output format to
for this technique to work.
This method is used by the author of PTLens.
The calibrate_lens tool also uses this technique and can operate with
images greater than 180°.
Taking a single photograph of a rectangular or grid object, selecting lots of
and , then optimising , , , , a, b & c. You need to set the output format to
for this technique to work.
The process is similar to this :
Taking two or more overlapping photographs and selecting lots of normal control points, then optimising , , , , a, b & c. This technique works with any output
but requires
free images shot exactly from the . Note that to get a precise measure of the , you have to take a full 360 degree panorama.
Using points that are known to be directly above each other such as edges of buildings, windows, reflections in ponds etc... This is the
method and works with
output and all lenses including those wider than 180°.
Using a tool such as PTLens, lensfun or
to read the photo
metadata and correct the image automatically by looking up the lens in an existing database.
If you optimize for lens correction in order to calibrate your lens you should keep some facts in mind:
Since lens correction parameters are determined by evaluating the distortion at different radius values you should provide enough control points at a large range of radii from the image center.
If you use a rectangular pattern or straight lines for that task, make sure you set control points in all distances from the center.
If you use two or more images make sure you overlap regions with large potential distortion (f.e. the corners) with regions with low possible distortion (f.e. the center). An only horizontal overlap would do, but use at least 50% in order to overlap the image center of one image with the border of the other.
a, b and c parameters influence , especially for images in landscape orientation but slightly for portrait oriented ones, too. This is because although the implicit calculation of the fourth polynomial parameter tries to keep the image at the same size, this is only possible at the radius r_src = 1.0.
Outside this radius, especially in the image corners, the size and hence the Field of View might differ. Since they are interconnected in this way, you should always allow the optimization for FoV too, if you optimize for a, b and c with more than one image. (You cannot optimize for FoV with only one image). As noted above you need a full 360 degree panorama in order to get an accurate measure of the .
The a and c parameters control more complex forms of distortion. In most cases it will be enough to optimize for the b parameter only, which is good at correcting normal
If you want to see how changing the parameters influences distortion correction go to
and get abc.xls. Don't deactivate macros on loading.
See also .
There's an excellent tutorial on how to optimize by John Houghton:
The original
can be scripted to batch process images with known a, b & c parameters.
It can also be operated with one of the GUI front-ends.
(part of the
distribution) can be used identically to .
The Correct Radial Shift filter in the Panorama Tools Plugins for the gimp or photoshop uses the same a, b & c parameters as .
Note that it doesn't know about d & e shift parameters and uses 'd' as an overall scaling factor instead, which should be d = 1-(a+b+c) to keep the image roughly the same size. If you need to shift the correction center like with the d & e parameter you must combine it with Vertical Shift and/or Horizontal Shift.
PTLens is a Photoshop plugin and a stand-alone Windows tool that uses the same a, b & c parameters and comes with a database of popular lenses.
Clens is a command line version of PTLens.
is a command-line tool that uses the same a, b, c & d parameters to correct .
It can also correct
at the same time.
PTShift determines different a, b & c parameters for the three color channels in order to correct for
with the Correct Radial Shift filter.
Gimp wideangle plugin uses a different formula altogether to correct distortion.
Gimp phfluuh plugin is another tool that corrects lens distortion using yet another formula.
CamChecker is a tool for automatically determining lens distortion and generates a different set of parameters from everything else.
zhang_undistort is a tool distributed with
that uses CamChecker parameters to actually correct distortion.
Distortion Remove uses a completely different approach with a distortion matrix. Page in german only:correction lens是什么意思_百度知道本文系微信公众号《大话成像》，知乎专栏《 all in camera》原创文章，转载请注明出处。我们经常比较头疼的是，图像的局部产生色偏，或者是某一个色调/亮度范围产生色偏。比如说第六题所提到的：只有蓝天的颜色发生了明显的偏差。造成局部偏差的原因有很多，比较常见的原因有两个：Lens shading和linearization。因为相较于black level或者awb这些global的操作造成整体性的变化，shading correction 和linearization往往是只造成局部区域和某个intensity范围的偏差。这些问题往往更难解决。这一篇就重点说说lens shading：Lens shading分为两个部分，luma shading correction，colour shading correction。Luma shading就是所谓的vignetting，镜头的通光量从中心到边角减小,造成sensor的亮度响应从中心到边角的变小，图像看起来就是这样，中心亮，四周逐渐变暗。colour shading是三个colour plane的shading 不能重合，导致的色彩偏差。correction之后：可以看出RGB plane 重合了。&luma shading的3D视图：这种信号强度的衰减呈现非常明显的中心对称特点，于是人们提出第一种shading 校正方法：radial shading correct。这种方法实现简单，针对shading对称性比较好的情况很有效，但是如果对于镜头装得倾斜了，或者存在局部不良的情况就不好用了。如下图很明显的衰减不对称，这样方法1就不好用了。于是有了方法2：拍一张黑色的照片，再拍一张白色的照片，然后用如下公式：由于响应衰减曲线不是线性的，而是近似cos4的衰减曲线，所以方法2需要对衰减曲线做一定的修正。但这种方法对于那种镜头衰减不能用一个简单函数表示的情况就不灵了。于是后来就有了方法3：mesh shading correction。mesh按照英文愿意就是网眼，渔网的那种格子。拍一张均匀亮度的图像，把图像分成n x m个格子，每个格子的四个角都有一个校正系数，把这个nxm个格子的校正系数存起来，在运行期，根据每个像素的坐标，就知道这个像素落在哪个格子里，在格子内部，用cos4或者logN来模拟衰减曲线，就可以计算出每个像素的校正值。现在大部分厂商都是采用的这种方法，它的缺点是需要存储比较多的校准数据，而且如果校准不准确的话，效果也就不会好。于是后来就有了方法4：automatic lens
shading correction。 也有人叫adaptive lens shading correction。反正就是不用校准，就能做lens shading correction。基本的公式如下：看起来唯一的玄机就在这个所谓的LowPass filter里，有很多论文设计不同的filter，唯一的目的就是把数据分成受shading 影响的和不受shading影响的，不受shading影响的数据就是校正的target。也有专门的论文提供各种比较结果。现在已经有不少公司提供这种不用校准的lens shading correction方案，效果确实非常不错。所以从出第六题的目的来说，并不是就事论事的回答一个问题，而是一个开放性的话题，讨论可能与之相关的技术问题。本文系微信公众号《大话成像》，知乎专栏《 all in camera》原创文章，转载请注明出处。光学影像世界(gh_f26d64280c47)　
　文章为作者独立观点，不代表微头条立场
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本文系微信公众号《大话成像》，知乎专栏《 all in camera》原创文章，转载请注明出处。我们经常比较MR增强了你眼前的真实世界，更无缝地把你眼前的一切混合在一起，可以让你更多地进行互动，它可以被看作是更高级的AR，但是跟VR基本就没什么关系。gh_f26d64280c47光学影像世界热门文章最新文章gh_f26d64280c47光学影像世界If you like and use our plugins, please support our effort by offering a paypal donation.
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This plugin corrects barrel and pincushion distortions that many& zoom camera lenses.produce.Just move the sliders to the left to correct barrel distortion, and to the right to correct pincushion .Many thanks to Martin Vicanek& who provided the code for this plugin. Here is an extreme fisheye& lens correction example submitted by a user:(other processing was also applied )
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