topic Re: How to start in GIS without previous knowledge and a defined problem? in Spatial Data Science Questions

How to start in GIS without previous knowledge and a defined problem?

HayleyHaydon — Wed, 09 Mar 2016 22:40:53 GMT

Hello there!

I'm absolute new in GIS and hope I'm right, coming here from wrtiting my thesis in environmental engineering. Therefore I need to calculate some values from a database (buildings in a part of a european city) available in QGIS in a grid of one km² per cell to get in the end the roughness of this part of the city.I assume, this is a standard operation in GIS (how many ... per km² are ... ), but I really have no idea how to start, and the company I work for isn't helping me.

So I would be very gratefull for some hints about what I need for solving this task. Like some important terms, etc. - I know that GIS is a complex science and I also want to engage, but first this is a concrete problem I need to solve quickly, so I don't have so much time to start a fulltime tutorial in QGIS.

I hope, there is someone who can help me with this!

Re: How to start in GIS without previous knowledge and a defined problem?

DarrenWiens2 — Wed, 09 Mar 2016 22:56:01 GMT

You should ask this question on a more general GIS forum, like: Geographic Information Systems Stack Exchange

...as this forum is specifically for ESRI ArcGIS software (similar, but different to QGIS) users.

Re: How to start in GIS without previous knowledge and a defined problem?

MelitaKennedy — Thu, 10 Mar 2016 00:06:52 GMT

A few hints, although I don't do much analysis.

1. What coordinate system is the building dataset using? You'll want it to be in a projected coordinate system (PCS or ProjCRS), localized as much as possible for the city. You might be able to use http://www.epsg-registry.org to get some ideas (likely none available for the city, but the country might have several zones. Note: the ProjCRS will likely be using meters for the units which leads into question 2.

2. Do you have the square kilometer grid yet? If not see if QGIS has a "fishnet" or grid tool to make a polygon-based dataset. ArcGIS does: Create Fishnet. Make it in meters so that it matches the ProjCRS from (1).

3. Then you can intersect or do some statistical analysis--I'm not sure of the correct terms here. You may also have to think about whether buildings that in two or more "cells" of the grid should be counted.

I hope this helps you to get started at least.

Melita

Re: How to start in GIS without previous knowledge and a defined problem?

DarrenWiens2 — Thu, 10 Mar 2016 00:17:44 GMT

Okay, if an ESRI employee is going to promote a QGIS answer then so will I.

The QGIS equivalent to ArcGIS fishnet is Create > Create Grid Layer within the MMQGIS plugin. It's a pretty cool tool that can also make a hexagon grid for you.

Re: How to start in GIS without previous knowledge and a defined problem?

MelitaKennedy — Thu, 10 Mar 2016 00:23:19 GMT

I've been a student struggling with software and a new field...! gis.SE can be a bit of a scrum too.