V-Ray DMC采样器原理释疑

各采样器比较

自适应细分是一个几乎所有其他“有偏差的非物理渲染器”（注1）都在采用的算法。它是一种相对来说有点老式，但在绝大多数情形下都非常好用的算法。它会算出干净且采样细致的图像结果，在静帧渲染时的表现非常出色，但是与DMC采样器相比，自适应细分往往会在一些本可以采样再少一点的地方过多采样
DMC采样器，那么要在某些同样的地方求出同样质量的反射模糊可能就不用这么多样本，DMC是目前在求取镜头景深和三维运动模糊时最好用（时间短质量高）的光线追踪采样算法

详解“采样”，自适应采样

计算机自己判断出在有必要的时候，才增加对个别像素的采样。这就是自适应采样技术，因为采样的数目是依据图像的复杂程度而适应性变化的。那么在颜色对比比较明显的地方采样数量会增加
自适应细分和DMC采样的共同点是它们都是自适应性的采样算法，但是工作机制不同

细分采样器

细分算法的采样点是处于如图所示的像素顶角上，初始样本采集到信息以后，细分采样器会分析这些信息，然后来决定哪些像素需要更多的采样样本。每一个像素边角上的样本都被拿来比较，如果某个像素的色差大于参数面板中设定的颜色阈值（下图所示），Vray就会进一步细分这个像素，并且在这个像素上采集更多的样本
难以理解，先放着

《沸腾十五年》

《沸腾十五年》讲述中国，1995-2009 1995互联网商业元年马云中国黄页杭州电信有着非常好的社会资源和政府资源，马云却一样都没有。杭州电信利用中国黄页（ chinapage.com ）已有的名声，做了一个名字很接近的网站，也叫“中国黄页”（ chinesepage.com ），借以分割马云版“中国黄页”的市场。海归、极客、商人成为中国互联网创业者中的三大特色群体（VC是推手） 1996海归归来为了确保搜狐不被遗忘，张朝阳选择了最便宜也最有效的方法：树立个人品牌。 1997大门洞开互联网的一年等于其他行业的7年网易免费电子邮箱系统一出，中关村性急的评论家们甚至给丁磊戴上第三代程序员的帽子，这个代别划分是这样的：基于DOS平台开发的是第一代，基于Windows平台开发的是第二代，基于Internet平台开发的是第三代。 1998极客当道曾李青是腾讯5个创始人中最好玩、最开放、最具激情和感召力的一个，与温和的马化腾、爱好技术的张志东相比，是另一个类型。周鸿祎在公开场合经常教育年轻的创业者，应该先用创业的心态去打工，充分积累自己在管理和业务上的能力和资源 1999狂欢开始了海归、商人、极客、VC推手，这四类人一起齐刷刷地汇聚在1999年，1999年就这样成为中国互联网最黄金、最灿烂、最辉煌、最值得念想的大年份。 2000泡沫四溢亚马逊的卖点是：‘最近50年的书我们都有’——这是它提供海量品种的意义。（因为国外有很高的信息化程度，以查询库房是否有存书）雷军在商店买T恤的时候，发现了求同消费现象。“中国经济和美国经济处在不同的发展阶段，美国消费者寻求个性消费，中国现阶段，需求高度趋同，中国需要50年前版书的人极少。” 单品价格压得再便宜，但5元钱的配送费卓越坚决不免，用户冲着几乎免费的产品而来，但想想既然要出5元的配送费，买一样商品是这个钱，10样商品也是，不如多挑几样商品。雷军发现，互联网比软件要好玩得多，可以不断地改，不断地去修正，用户可以很快地反馈给你，你也可以很快地进步 2001大转折段永平反问他：“你卖了公司之后干吗？”丁磊说：“我卖了公司有钱后再开一家公司。” 段永平发现，网易股票被低估是因为公司面临一场官司，也可能被摘牌，这里面有些不确定性。段永平就去找一些法律界人士问官司的问题，问类似的官司最可能的结果是什么，得到...

阅读全文

产品随想 | 陪读《芯片战争》：一、二章

作者其它书也值得读读已出版《食用油营销第1书》《金龙鱼背后的粮油帝国》《鲁花：一粒花生撬动的粮油帝国》《手机战争》等财经书籍。第一章从晶体管到芯片肖克利要创业的消息，就像17世纪的牛顿宣布要建立工场一样引起了轰动。那时候，美国还在草创时期的半导体产业主要集中在东部的波士顿和纽约长岛地区，许多科学家和工程师精英都慕肖克利之名前往美国西海岸，不远千里地聚集在肖克利旗下。可以这么说，肖克利给硅谷带来了最初的火种。 ——我也認可這個說法，不是斯坦福或其他校園，純粹是人才的原因芯片发明后的六年间，政府对芯片项目的资助高达3200万美元，其中70%来自空军。同期美国半导体产业的研发经费有约85%的比例来自政府，政府的支持成就了美国在半导体领域的技术优势。“华盛顿通过支付技术研发费用和保证最终产品的市场份额，将原子弹最终制造成功的间隔缩短至六年，晶体管缩短至五年，集成电路缩短至三年。”不过，这些半导体企业实力壮大以后，往往不愿再参与美国政府出资的研发项目，因为那意味着专利权归政府所有，而且还得受保密条款的约束。 ——這纔是更合理的產業支持政策诺伊斯采用激进的价格政策，将主要芯片产品的价格一举降到1美元，不仅是市场上的主流芯片价格的零头，还低于当时芯片的成本。这不是传统意义上的亏本倾销，而是第一个以反摩尔定律为定价依据的案例。反摩尔定律认为，同样的芯片在18个月后价格就会跌一半，所以按照几年后的价格为当前的芯片定价是有一定合理性的。市场被迅速打开，芯片很快在民用市场得到越来越广泛的应用，仙童的营收和利润都迅速上升，还带动了其母公司的股价上涨。摩尔后来评论：“诺伊斯以低价刺激需求，继而扩大产能、降低成本的策略，对于芯片产业的发展而言，其重要性堪比芯片的发明。” ——看到這裏的時候，真是非常震撼，好厲害的定價策略东通工用磷渗透法研发出了高频的晶体管，于1957年做出世界上第一款袖珍收音机，并在这款产品上启用了索尼商标。盛田昭夫到美国去推销袖珍收音机的时候，德州仪器刚刚轻率地放弃了这个市场。美国人对盛田昭夫说：你们为什么要制造这种小收音机？美国人都想要大收音机。盛田昭夫回答：单单纽约就有20多家广播公司，同时就有20多套节目在播放，每人使用一台小收音机收听自己喜欢的节目，岂不更好？索尼用“一人一台”的宣传成功打破了美国人全家共用一台大型收音机的观念，成为全世界最畅销的收音机...

阅读全文

产品随想 | 周刊第116期：Great things in business are never done by one person.

Cromite https://github.com/uazo/cromite Cromite a Bromite fork with ad blocking and privacy enhancements; take back your browser! awesome-shizuku https://github.com/timschneeb/awesome-shizuku Curated list of awesome Android apps making use of Shizuku KernelSU https://github.com/tiann/KernelSU A Kernel based root solution for Android Love, Hate or Fear It, TikTok Has Changed America https://www.nytimes.com/interactive/2024/04/18/business/media/tiktok-ban-american-culture.html?unlocked_article_code=1.mE0.DpEZ.VWmNssw5B6_c "My model for business is The Beatles.There were four guys who kept each others, kind of, negative tendencies in check. They balanced each other, and the total was greater than the sum of the parts. And that's how I see business. You know, great things in business are never done by one person. They're done by a team of people. "Our motivation is simple--we want to provide the most advanced and innovative platform to our developers, and we wa...

阅读全文

产品随想 | 周刊第117期：He saw the intersection of art and science and business and built an organization to reflect that.

He disliked biography attempts. “I regard my scientific papers as my essential biography,’’ Land said. “I pour my whole life into the scientific project I’m investigating. I leave behind the things I’ve done in the past to do the work in the present.’’ “The purpose of inventing instant photography was essentially aesthetic,’’ Land said in 1947, announcing the process’s invention. “We live in a world changing so rapidly that what we mean frequently by common sense is doing the thing that would have been right last year.” — Edwin Land, Statement to Polaroid Corporation employees (25 June 1958) The worldview he was describing perfectly echoed Land’s: “Market research is what you do when your product isn’t any good.” And his sense of innovation: “Every significant invention,” Land once said, “must be startling, unexpected, and must come into a world that is not prepared for it. If the world were prepared for it, it would not be much of an invention.” Thirty years later, when a reporter ask...

阅读全文

Scott Forstall: "Great leaders exude a positive attitude of possibility and don’t shy from working harder than their employees and taking risks."

Scott Forstall led the team at Apple that developed the iPhone – and is equally successful in vastly different realms, including co-producing multiple Tony Award winning Broadway shows. What has always impressed me most, though, is the time he devotes to mentoring a diverse set of entrepreneurial founders. We’ve had the pleasure of knowing each other for several years, thanks to mutual friend Ali Partovi ’s incredible Neo community , a mentor community, accelerator and VC through which we support junior engineers to become senior leaders. Ali was an early backer of Airbnb, Dropbox, Uber and Facebook, so I knew I was in good hands! At our recent Neo reunion I was able to catch-up with Scott for a wide-ranging conversation on the landscapes of opportunity in technology and what we’re anticipating next. He kindly agreed to go o...

阅读全文

“真假难辨”的效果图如何打造，以一只笔为例（下）——渲染篇

原文地址独家教程 | “真假难辨”的效果图如何打造，以一只笔为例（下）——渲染篇上期独家教程，康石石带大家用Rhino完成了 COPIC MULTILINER 针管笔建模（复习请戳：独家教程 | “真假难辨”的效果图如何打造，以一只笔为例（上）——建模篇），下面我们把它丢进Keyshot渲染器里，看看究竟Keyshot究竟能不能打造真实照片一般的既视感。 Keyshot虽为各家晚辈，但近年来突飞猛进。有的同学说Keyshot渲染效果不如V-Ray，但我们可以看下本期独家教程内容再作判断。基础材质赋予首先我们打开 Keyshot 基本导入参数导入后由于我们事先在Rhino中，对各个部件分过色，所以我们可以直接，尽情把左边各种需要的材质球直接拖到需要的部件上。初步赋予材质后效果特写效果环境光赋予 Keyshot预设的材质显然不能够完全适合所需情况，且物体上的光线并不是很正确。因此同学们需要将环境光换成更加接近真实摄影棚的灯光场景。选用 3 Panels Tilted 2k 作为的基本环境光，将环境光拖入环境里之后，效果如下：模型各部材质赋予由于光影的变化，整个模型已更加真实。接下来各部的材质还需根据实际的视觉情况手工调整。以下是这次模型各部材质的参数：笔身主要的金属材质黑色塑料件部分以及笔头的黑色笔夹与笔头所使用的金属材质 Tip：金属材质是将Keyshot预设的钢材质的粗糙度调整为0.01而成。握柄处的塑料材质 Tip：因为塑料的视觉特点，此处特地选用了半透明属性的材质做调整，除了表面颜色的参数之外，剩余的三个颜色区域均使用了 R255，G255，B255的纯白。笔身标签渲染在给各部赋予了材质之后，产品很重要的一个环节就是印刷于产品之上的各种商标与说明，在Keyshot中，这些效果可以很轻松的通过标签功能来实现。首先对实物上的印刷效果进行观察，可以看出实物上的印刷效果其实是比较立体的。 Tip：细节，往往是产品品质的一种体现。在效果图的渲染中，也应该...

阅读全文

巴菲特致股东信-1971年

编者笔记：保险业务因为高毛利，开始有了更多竞争（资本逐利性）确保当保险灾难来临时，有能力调集足够的资金来解决巴菲特几乎从不进行恶意收购，收购的主要目的是：长期持有企业以获得经营利润并利用自由现金流再投资原文： https://xueqiu.com/6217262310/131103035 To the Stockholders of Berkshire Hathaway Inc.: It is a pleasure to report that operating earnings in 1971, excluding capital gains, amounted to more than 14% of beginning shareholders' equity. This result--considerably above the average of American industry--was achieved in the face of inadequate earnings in our textile operation, making clear the benefits of redeployment of capital inaugurated five years ago. It will continue to be the objective of management to improve return on total capitalization (long term debt plus equity), as well as the return on equity capital. However, it should be realized that merely maintaining the present relatively high rate of return may well prove more difficult than was improvement from the very low levels of return which prevailed throughout most of the 1960's. ...

阅读全文

《Becoming Steve Jobs》Chapter 11 Do Your Level Best

As a mass-market consumer electronics device, the iPod would eventually be sold, of course, all the usual places: Best Buy, Circuit City, big-box department stores, and even the computer retailers like CompUSA. Steve disdained all these outlets. His obsession with his products continued well after they’d been manufactured. The tacky, low-margin hustle of these chains ran completely against the minimalist aesthetic of his products and the clean exuberance of his marketing. There was only one place where he really enjoyed seeing his products sold to the public: his own Apple stores, which had debuted four months ahead of the iPod. 觉得那些喧嚣、嘈杂的零售渠道，配不上自己极美的产品 Going back as far as the debut of the Mac, Steve had always groused about the way Apple computers were sold in its resellers’ stores. The way his computers were displayed and sold represented the very worst of what could go wrong when things weren’t done his way. The salespeople, always interested in quick turnover, seemed to make litt...

阅读全文

Steve Jobs on the iTunes Music Store: The Unpublished Interview

A candid talk with Apple's CEO on a landmark day in its history. By Laura Locke | Wednesday, December 7, 2011 at 1:15 am Steve Jobs announces the iTunes Music Store. On April 28th, 2003, moments before I was about to interview Steve Jobs at San Francisco’s Moscone Center, I was jittery. Anticipation? Nerves? Excitement? You bet. All of those visceral emotions were firing. Knowing Jobs’ storied reputation as an irascible and exacting Silicon Valley CEO had me on edge. But I had prepared a tight set of questions. Secretly, I was hoping he might enjoy the line of inquiry. In turn, I would have a lively and candid report for my editors at TIME. What I didn’t know was that the interview was taking place on what would turn out to be one of the most important days in Apple’s history: The launch of the iTunes Music Store. Once again, Ste...

阅读全文

产品随想 | 周刊第50期：2010年kkndme：写在房价暴涨前

Products Digital Clock 4 https://sourceforge.net/projects/digitalclock4/ 开源的桌面时钟工具，开源，Linux, Mac, Windows FlipIt https://github.com/phaselden/FlipIt Flip Clock screensaver 开源的翻页时钟 Windows 11 Fixer https://github.com/99natmar99/Windows-11-Fixer Windows 11 Fixer is a program designed to make customizing your Windows 11 as easy as possible. 在一个集中的位置，能直接Win11相关的设置即食历史 https://cuphistory.net/ 非常简短的历史科普，Base香港，很多内容有广东话 kkndme聊房 https://github.com/momo0853/kkndme kkndme聊房，数据整理自天涯。提供HTML、PDF和Markdown三种形式。 v86 https://github.com/copy/v86 x86 virtualization in your browser, recompiling x86 to wasm on the fly 浏览器中模拟x86 GitHub City https://github.com/honzaap/GithubCity Create a 3D city from your GitHub contributions 让过往成城 Layoffs.fyi Tracker https://layoffs.fyi/ Tracking all tech startup layoffs since COVID-19. 用技术，监测疫情依赖的美国科技公司裁员 Trianglify https://github.com/qrohlf/trianglify Algorithmically generated triangle art Low Poly生成工具...

阅读全文

产品随想的博客

搜索此博客