transformation

rotate 3D on X in Flutter

由 ╄→尐↘猪︶ㄣ 提交于 2020-02-20 04:44:13
问题 I've been working with Flutter rotation, new Matrix4.identity() ..rotateX(degrees * 3.1415927 / 180), but, the problem, I want it to be similar to the diagram below. can I achieve a 3D-like rotation on the x-axis with Flutter? even if there is a mapping from 3D to 2D or there are alternatives that would get the same result. thanks in advance. Example image in OpenCV: How to calculate perspective transform for OpenCV from rotation angles? 回答1: thanks to this discussion, and this repo, and

仿射变换(Affine Transformation)

由 旧街凉风 提交于 2020-01-31 05:10:35
仿射变换(Affine Transformation) 变换模型是指根据待匹配图像与背景图像之间几何畸变的情况，所选择的能最佳拟合两幅图像之间变化的几何变换模型。可采用的变换模型有如下几种:刚性变换、仿射变换、透视变换和非线形变换等，如下图： 参考： http://wenku.baidu.com/view/826a796027d3240c8447ef20.html 其中第三个的仿射变换就是我们这节要讨论的。 仿射变换(Affine Transformation) Affine Transformation是一种二维坐标到二维坐标之间的线性变换，保持二维图形的“平直性”（译注：straightness，即变换后直线还是直线不会打弯，圆弧还是圆弧）和“平行性”（译注：parallelness，其实是指保二维图形间的相对位置关系不变，平行线还是平行线，相交直线的交角不变。）。 c和d的区别可以看下图： 仿射变换可以通过一系列的原子变换的复合来实现，包括：平移（Translation）、缩放（Scale）、翻转（Flip）、旋转（Rotation）和剪切（Shear）。 仿射变换可以用下面公式表示： 参考： http://wenku.baidu.com/view/826a796027d3240c8447ef20.html 这个矩阵乘法的计算如下： 具体到二维的仿射变换的计算如下：

Java Pentaho Exception MongoDB

由 痴心易碎 提交于 2020-01-26 00:17:47
问题 I have designed a transformation in Pentaho Data Integration ui tool and wrote a java code to execute the transformation. I followed below resources link as it is, try { /** * Initialize the Kettle Enviornment */ KettleEnvironment.init(); /** * Create a trans object to properly assign the ktr metadata. * * @filedb: The ktr file path to be executed. * */ TransMeta metadata = new TransMeta("Districts.ktr"); Trans trans = new Trans(metadata); // Execute the transformation trans.execute(null);

how transform from xml to json with xsl and removing the item/record labels

由 北城以北 提交于 2020-01-25 18:48:33
问题 Thanks to the excellent answer provided by Tim C in how transform from xml based on attributes to json and ignore the attributes from especific elements by using XSLT/XSL, I could learn how to transform my input xml to a json and excluding the item attributes during transformation. Kindly, see the input xml file below. Please, how can I do exact same transformation but ignoring the "aa" and "bbb" in the output json? I mean, how do I exclude during xml transformation to json the record

Transform to numeric a column with “NULL” values

由 為{幸葍}努か 提交于 2020-01-24 21:22:26
问题 I've imported a dataset into R where in a column which should be supposed to contain numeric values are present NULL . This make R set the column class to character or factor depending on if you are using or not the stringAsFactors argument. To give you and idea this is the structure of the dataset. > str(data) 'data.frame': 1016 obs. of 10 variables: $ Date : Date, format: "2014-01-01" "2014-01-01" "2014-01-01" "2014-01-01" ... $ Name : chr "Chi" "Chi" "Chi" "Chi" ... $ Impressions: chr

questions of transform matrix in VR

由 笑着哭i 提交于 2020-01-24 12:27:07
问题 I have a problem about matrix transformation in OpenVR api. m_compositor->WaitGetPoses(m_rTrackedDevicePose, vr::k_unMaxTrackedDeviceCount, nullptr, 0); in the demo which the openvr gives: const Matrix4 & matDeviceToTracking = m_rmat4DevicePose[ unTrackedDevice ]; Matrix4 matMVP = GetCurrentViewProjectionMatrix( nEye ) * matDeviceToTracking; glUniformMatrix4fv( m_nRenderModelMatrixLocation, 1, GL_FALSE, matMVP.get() ); where GetCurrentViewProjectionMatrix is calculated with Matrix4

Calculate a Homography with only Translation, Rotation and Scale in Opencv

由 大憨熊 提交于 2020-01-22 09:56:18
问题 I do have two sets of points and I want to find the best transformation between them. In OpenCV, you have the following function: Mat H = Calib3d.findHomography(src_points, dest_points); that returns you a 3x3 Homography matrix, using RANSAC. My problem is now, that I only need translation and rotation (& maybe scale), I don't need affine and perspective. The thing is, my points are only in 2D. (1) Is there a function to compute something like a homography but with less degrees of freedom? (2

Calculate a Homography with only Translation, Rotation and Scale in Opencv

由 冷暖自知 提交于 2020-01-22 09:56:09
问题 I do have two sets of points and I want to find the best transformation between them. In OpenCV, you have the following function: Mat H = Calib3d.findHomography(src_points, dest_points); that returns you a 3x3 Homography matrix, using RANSAC. My problem is now, that I only need translation and rotation (& maybe scale), I don't need affine and perspective. The thing is, my points are only in 2D. (1) Is there a function to compute something like a homography but with less degrees of freedom? (2

Java to Json validation using GSON

由 帅比萌擦擦* 提交于 2020-01-21 05:25:08
问题 While converting Java object to Json string using GSON API, I also want to fail this Json conversion if any of the annotated attribute is null. For example public class Order{ @SerializedName("orderId") @Expose @Required private Integer id; //getter & setter available for id } Now as I am doing Order order = new Order(); JSONObject jsonobj = new JSONObject(gson.toJson(order)); I want to fail the above Java to Json transformation if any of the @Required attribute is null Is this possible using

How can I convert a date in Epoch to “Y-m-d H:i:s” in Javascript?

由 醉酒当歌 提交于 2020-01-21 02:39:09
问题 How can I convert following date in epoch: 1293683278 to following readable date: 2010-06-23 09:57:58 using Javascript? Thanks! 回答1: var timestamp = 1293683278; var date = new Date(timestamp * 1000); var year = date.getFullYear(); var month = date.getMonth() + 1; var day = date.getDate(); var hours = date.getHours(); var minutes = date.getMinutes(); var seconds = date.getSeconds(); console.log(year + "-" + month + "-" + day + " " + hours + ":" + minutes + ":" + seconds); See js Date docs for
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