Avenza Resources Blog
The Mosaic function in Geographic Imager merges multiple georeferenced images together to create a single composite georeferenced image. Though the goal of the mosaic is to create a single and seamless composite image, combining images with the Mosaic tool will often result in a slight shift of the imagery due to differences in the original pixel registration grid. This means that even when images are in the same coordinate system with the same spatial resolution, error can still be introduced because of a difference in the pixel alignment. Due to this, mosaicking processes in general tend to produce results that may be very close, but not exact. With this in mind, the results of your mosaic may be improved by resampling your images beforehand to the smallest unit of the resolution.
As an example, let's say we have an image where the pixel size is 2.00 metres. When plotting the X coordinates of every pixel in this image (using the top left corner of the pixel), the X coordinate value will be incremented by the number/distance of the pixel size. For example, if the X coordinate values were to start at 111.00, then the next pixel would be 113.00, 115.00, 117.00, and so on. It's important to note that these coordinate values are discrete, which means that the values could not be 113.22 or 115.77 because the origin of the coordinate in this case starts at 111.00 metres.
Have you ever imported data that doesn't quite line up how you'd expect? It may be that you've fallen victim to a common workflow error when importing GIS data. Some file types such as CSV can be used for GIS data but don't contain coordinate system information. When you are importing data from this format, you first have to define the correct coordinate system.
In this example, we're going to look at the common mistakes people make and how to avoid them. We'll start with a world map in the Robinson projection.
Do you have pictures and images you want to insert as an attribute in MAPublisher?
MAPublisher 9.4 introduces a new data type called Image. To work with the Image data type, you'll have to take a look in the MAP Attributes panel. The Image data type can be used in the same way as the other data types in the MAP Attributes panel. Use the Edit Schema dialog box to edit or create the Image data type as an attribute.
For this example, we have a point layer called "Point of Interests". Let's create a new attribute column with Image data type called "Picture".
In MAPublisher, the grid bound is the visual extent of the grid or graticule. The grid constraint is the geographic extent of the grid or graticule. It may be a little confusing since both grid bound and grid constraint are defined by coordinate values. In terms of hierarchy, think of the grid bound as the overall container of the grid and the constraint as being contained within the bound.
Have you ever had a point dataset where you wanted to obtain the elevation information for every point?
It's exciting when a new version of MAPublisher is released! However, after upgrading you might come across a license status indicated as "License version too low" in the MAPublisher Welcome screen (above) or the License Management dialog box (below). Why? This is most likely due to not obtaining a license for the latest version of MAPublisher yet.
Here's a short and simple video on how to export an ArcGIS map for use in the PDF Maps app. It was put together by the Smith College Spatial Analysis Lab. It uses a live USGS topo basemap streaming from Esri and the geospatial PDF export feature of ArcGIS.
Do you have some data you would like to divide into multiple layers using unique values in an attribute? If so, you might want to try using the Split Layer feature in MAPublisher.
In a previous blog about Grids and Graticules, we quickly introduced one of the major features of the new Grid and Graticule tool. We'd like to share another major feature when creating grids: creating grids with an alternative coordinate system.
For example, the MAP View has a coordinate system "NAD 83 / UTM zone 17N" (in metres). You might want to make grid lines with the same coordinate system but in different units. You can do so by creating a custom coordinate system and then specifying the desired unit (US Foot, for this example), then creating a grid based on custom coordinate system. In this example, a grid with NAD83/UTM zone 17N (metres) coordinate system is created in the blue colour. Another grid with a NAD83/UTM zone 17N (USFoot) custom coordinate system is created with the orange colour.