We will use ArcHydro to calculate the different whatersheds of a given territory. It is not only important to know the different steps to achieve the desired result, but also the assumptions we will be using. Indeed, they are not privative of ArcHydro, however they are the only ones available. Continue reading “ArcHydro: determination of the watersheds of a territory (1)”
ArcHydro is a set of data models and tools that work under ARCGis to support the data analysis of superficial water resources.
You can use ArcHydro to delineate and characterize the watershed lines, define and analyze the hydrogeometric network, manage the chronological data and export data to digital models. Continue reading “ArcHydro: how to model the water resources of a territory: 1-Install”
KML(Keyhole Markup Language) is an XML data format used to display information in a geographical context. Just as Web browsers read and display HTML files, land-based browsers such as Google Earth read and display KML files. KML is a language readable byeveryone , composed of text and punctuation . It can be created and edited through a basic text editor, saved, and then previewed in a land-based browser . You do not need to be a wizard to master the basics of KML, and you’ll notice than this knowledge will make it possible to create powerful presentations that depict your geographical data and images on the numerous land-based free browsers such as : Google Earth, Microsoft Virtual Earth, NASA WorldWind, ArcGisExplorer, .. Continue reading “KML: Getting Started”
Thanks to the SRTM project we can access to a comprehensive world coverage of land elevation data. It has become very simple to create one’s own topographic maps with QGis .
We will discuss here :
- – how to download elevation data for the area of interest
- – how to format the display style to fit the standards of the topographic maps
- – how to enhance the viewing using a “shady” layer type
- – and finally how to generate contours Continue reading “Make a topographic map with QGis”
In the previous article (Le Cube spatio-temporel d’ArcGis : 1- découverte) we discussed how to create a spatial-temporal cube from a cloud of XYZ points.
The points are grouped into ” boxes ” (bins) corresponding to 3D pixels.
We have discussed how to depict them in an ArcGis Pro 3D scene. In this article we will discuss how to analyze the temporal trends of the bins values, using the analysis of emerging hot spots. Continue reading “The spatial-temporal cube of ArcGis : 2- Hot and Cold Spots”
One of the domains of GIS where still remains a lot to be done is the field of temporal analysis . While almost all the available tools focus on the spatial evolution of a phenomenon, we are left helpless when trying to visualize or analyse a phenomenon that changes as a function of time as well.
For some time, we have the support of animation tools that allow us to see a sequence of maps and perceive the change over time. Regardless of how useful they are for communication, they are useless to perform a serious data analysis. In this series of articles, we will discuss new ArcMap and ArcGis Pro tools available in the form of a Toolkit Tools model for the spatial-temporal exploration (Time Pattern Mining). An example has been selected in order to process, at first with ArcGis Pro, and, later, with ArcMap. Continue reading “The spatial-temporal cube of ArcGis : 1- discovery”
Unlike in a previous article (Spatial Data Analysis and Spatial Analysis of Data) where nothing was specific to coastal management, in this article I will examine specifically Coastal Management. We will start by discussing how geomatics applied to the littoral zone displays very specific features.
QField allows you to do fieldwork on QGis projects with Android phones or tablets.
In this article we will discuss how to install QField on a mobile device and how to install and work on a QGis project. Continue reading “QField: the mobile device of QGis for Android”
If you start to feel tired of managing your data as shape files (this format dates back to the eighties!) and you yearn for a genuine database for your projects, most certainly, you will be looking to use PostGis. There is a big gap, and the ‘jump’ is, by no means, an easy one. In this article, we will discuss an alternative solution, the SpatiaLite database. And, believe me, it is much more easier…. Continue reading “How to create a SpatiaLite database with QGis”
We have already discussed the topic of geometry validation through a series of articles (in french):
- GIS tools for validation of geometries (1)
- Geometry validation GIS tools (2): Spatiality and PostGis
- Geometry validation tools (3): FME
- Geometry validation tools (4): Geomedia Intergraph
- Geometry validation tools (5) with QGis
In this article we will discuss, in detail, how to detect and rectify geometric problems in a PostgreSQL / Postgis table using SQL queries.
Continue reading “How to rectify the geometry of a Postgis table”