17种方式是栅格大师

关于栅格的美丽事情是它们对于可视化和数学分析非常有用。They’re simple, versatile, and the best way to represent data on a continuous, pixel-by-pixel basis.

Here are a bunch of ways you can work with this data type—and I hope the list inspires you to think of even more possibilities. You’ll see how to重组rasters to get exactly what you need, exerting specific control over cells, bands, palettes, even the way they’re geocoded. You’ll also see many ways tointegratethem, resulting in datasets that are much more rich and illustrative. If you hang around long enough, you might even learn how to use math and expression evaluation to impress your friends.

1. Convert between data formats

This GeoTIFF has been converted from a layered DWG, creating an image of the vector that better meets structural requirements.

有很多栅格格式。我不想通过猜测有多少（在那些果冻豆罐猜游戏中一直可怕）来尴尬，但我可以告诉你FME合作超过60他们。我们使用统计数据中最受欢迎的是地理灯/ TIFF和ECW。

要得到数据集成的所有好处,通常是值得转换程序er raster format, or translating between raster and vector, or combining rasters with point clouds, databases, CAD, GIS, or any other data type. In a world wheredata is liquid, it’s suicide to keep information locked in a single format.

2. Change the dimensions

这是一个已经向下采样至10×10的25×25个DEM的视觉表示。

Resample the image to your desired row/column dimensions, cell size, or percentage of the original size. Resampling is usually done to generate a smaller image, but it can also be used to make a bigger (though lower quality) one.

Unless you’re looking to make pixel art, you’ll want to get essentially the same representation of a picture (for a color image) or value distribution (for a numeric raster) when downsampling. Useful interpolation methods include nearest neighbor (fast), bicubic (best quality), bilinear (a compromise), and average 4 or 16 (good for numeric rasters like DEMs).

3.更改坐标系

LAT / LONG投影可能是我们的使用统计数据中最受欢迎的，但不同的任务需要不同的坐标系。

Like any worthy, respectable spatial data format, rasters can be georeferenced and can come in a variety of coordinate systems.

If you need to project the graphics onto a map or combine it with other data, you can reproject it to another system. For example, KML requires WGS84 (LL84), while tiles in a Web Map Tile Service are likely in Spherical Mercator.

如果您想要真正具体，您甚至可以控制您的光栅的地理编码。例如，一些栅格嵌入有地面控制点（GCP），而不是在角落上具有地理码。您可以根据需要提取或设置GCP。

4. Combine tiles into one image

Mosaicking means bringing multiple images together. At Safe, this is our most popular raster transformation.

Mosaic multiple rasters into a single feature. For example, maybe you need to bring tiles together into a simple overview in a lat/long projection. This would involve a mosaic, resample (#2), and reproject (#3) transformation.

It’s like a puzzle! One where the pieces don’t really fit together!

是的。关于那个。Reproject可以略微旋转图像，然后何时摩擦，我们经常在碎片之间留下空的黑色区域。一个强迫症的噩梦。别担心。您可以通过添加“Nodata”值来修复它，因此空区域变得透明并拾取下面的背景。

This image has been compressed to make it easier to work with while not reducing quality.

5. Compress raster files

Like putting your raster in Spanx, compressing it makes everything slimmer and trimmer. 75% is a pretty good ratio to use if you want a smaller image that’s quicker to process, but still good quality.

许多格式支持压缩：JPEG / JPEG2000，ECW，地理灯/ TIFF，Oracle Spatial Georaster，ArcSDE栅格，地理数据库栅格，CADRG和WEPP命名十。

6. Clip to boundaries

Clipping is essentially a combination of rasters and vectors to produce more useful output. For instance, each of these clipped pieces can be stored in a PostGIS database with its associated metadata.

Clip an image to keep only the pieces you need, and toss away the parts outside of your defined boundary.

例如，您可以使用定义海岸线的多边形合并加利福尼亚ecw，并夹住海洋（无论如何需要那个大蓝潮湿的东西吗？）。结果将是刚才的形象。

如果你剪断许多地区,像公园boundaries, you can merge the attributes from the vector features so each clipped piece retains all the properties, like the park name. As mentioned in #4, it’s handy to define the empty pieces as “nodata” so they stay transparent, making it easy to view over a background map.

Check outfme.ly/parks.查看图像和元数据的样本HTML目录。

7.制作光栅图形和/或元数据的目录

Consolidate graphics and their properties into a useful place, one you can share with your mom to show her all the cool stuff you do at work.

To see what I mean, check outfme.ly/parks.. That’s a catalog of a bunch of clipped images and information on each piece.

目录从不支持图像的数据库中将栅格作为二进制blob读取，然后使用一些简单的html来使一切都看起来很好。

这个GIF已经平铺，导致碎片输出相同。阴影被夸大，以区分瓷砖。

8.将一个大图像分成瓷砖

Split a raster into a series of tiles. Maybe you want images in a particular size, or maybe you want a particular number. Maybe you need smaller pieces for processing. Maybe you need to load your raster in software that doesn’t support highly compressed wavelengths. Maybe you just like your data in really tiny pieces—like data confetti. I don’t blame you. Confetti is fun.

Whatever your situation, you have a giant image and you want it in smaller pieces. Tile it.

The most commonly used web map tiling scheme is the谷歌和Bing地图兼容一。

9. Create a web map tile service

创建一系列可通过Web映射应用程序使用的图像块，例如Google地图，Bing映射或其他Web地图图块服务。

WMT中的图像存储在瓷砖集中，因此在缩放时，您会看到不同分辨率的不同瓦片集。您可以通过恢复球形Mercator（＃3），以重新采样来创建一个WMTS，以各种分辨率（＃2），并拆分为瓷砖（＃8）。

10. Texture a geometric surface

This 3D model is the result of a multi-step raster transformation: a JPEG draped onto a TIN surface that was generated from a DEM.

我觉得没有栅格已经实现了它的命运，直到它被用来纹理表面。首先，Rasters是3D世界的2D表示。其次，3D模型通常是普通和织物的。也没有像它一样有帮助。在3D模型上覆盖光栅通常是一个启发整合。

假设你有一个轮廓的ESRI Shapefile，以及MRSID Orthophoto。您可以通过基于高程将轮廓转换为3D来创建DEM。当生成为锡并与原子光电子集成时，您最终通过具有纹理表面的更有用的3D模型，如右侧的糖果山。

用RGB和DEM Rasters揭示点云也导致一些伟大的表面模型转换（我们最受欢迎的一个莱达processing tasks).

11.将图像作为特征的属性附加

Esri ArcGIS supports the ability to add attachments in aGeodatabase要素类。

A lot of formats, likeGeodatabase或Excel，允许图像附件。

This is great news for interoperability, because you can make a raster out of anything. Photos, scans, statistical data, charts, illustrations, satellite imagery … One time I demoed an enterprise raster reader/writer using a picture of a pony.

任何可以进入栅格的任何东西都可以以支持图像附件的格式。

该32位RGBA PNG已被转换为具有α频带，因此它可以代表透明度。这种类型的“羽化”在拼接时可以有用。

12. Restructure the bands

Ok, now we’re getting into some more powerful stuff. (Puts on sunglasses.)

If you have multi-band data and you need to convert to a format that doesn’t support it—for example, if you have an intense 8-band format but all you want is an RGB overview—you can remove bands you don’t need.

您还可以重新介绍或添加频带，例如以具有透明度的RGB从RGB重新介绍，或删除Alpha Band，以便使用普通RGB。

在该示例中，用户基于DEM中的值生成一组矢量多边形。

13.根据值矢量化光栅

One way to convert raster to vector is to create a polygon for each contiguous area of pixels with the same value. We call this classifying a raster.

In the vector image on the right, polygons were generated by rounding off the nearest 25 meters in the elevation model before classifying. NURBS were then made from the polygons, resulting in a vectorized contour map.

Either that, or someone put a rainbow in a blender. I’m not sure.

此加拿大数字海拔数据已被山丘阴影，然后覆盖背景图。

14.用山丘遮荫制作位图逼真

如果您使用高程数据，您可能熟悉普通，黑白图形，高海拔是白色，低海拔是黑色的。对不起，甚至3D眼镜也不能让那东西看起来3D。相信我，我试过。

Hill shading offers a real-world rendering of what the picture actually looks like. This is particularly useful for visualizing terrain when putting together a cartographic product.

15. Colorize point clouds

This point cloud has been colorized with a raster.

数据集就像香料，直到将它们混合在一起，你不经历完整的味道。

Overlay a point cloud on a georeferenced raster to color the points.

结合栅格和点云使LIDAR可视化更加令人欣喜。看看我的博客帖子14 Ways to Take Charge of LiDAR Data看到许多方法来整合点云。一些最有用的，漂亮的产出涉及栅格。

These red polygons were overlaid based on algebra performed to identify areas of interest.

16. Pixel by pixel expression evaluation

Perform calculations based on the value of one or more cells. For example, you can calculate the slope or aspect (direction of slope) for each cell, or extract the extents, or detect changes between two inputs.

您还可以根据算法修改像素值。是的，朋友，如果这些像素存储RGB值，那么这只是一个奇特的方式说“让自己的瓦伦西亚或X-Pro II”。向任何使用栅格表达式评估的人提供自己的Instagram过滤器的免费spork。

通过将路段值从路映像复制到背景层来组合一个地理灯和PNG。

17.通过复制单元或使用半透明层或使用半透明层栅格

组合两个栅格以查看两层的信息。您可以通过仅从其中一个图像（例如，白色和黄色道路）或通过添加透明度（＃12）来完成此操作。Alpha Band允许您在覆盖它们时平滑融合图像。有点像数字铁上的转移纸。

要查看如何使用FME完成上述所有任务，请访问亚搏在线safe.com/瑞斯特. I recommend you watch this October 2013网络研讨会记录对于伟大的现场演示，包括结合多个数据源（包括WMS），高级转换和数学的令人印象深刻的方案。我们还有一系列巨大的文章FME社亚搏国际在线官网区帮助您完成光栅需求。

What kind of translations and transformations do you do with raster data? What do you find the most challenging?

天安华纳

天籁是安全软件的高级营销专家。亚搏在线她在计算机编程和创意爱好中的背景使她成为安全软件的创造性内容的主要生产商之一。亚搏在线天纳花了她的空闲时间，写幻想小说，骑马，与她的救援小狗，乔伊探索自然。