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QGIS mapping

2022-06-29 10:15:00 【Chennan giser】

Hello everyone , I'm Nannan , This is south south 2022 The second tweet of summer vacation

Data download

You can get it from the website below , World geological map

https://certmapper.cr.usgs.gov/data/apps/world-maps/

Here you can Shapefile Download geological maps from all parts of the world

Of course , Some others, such as faults , Structure and other information , It's very simple , Below is the geological data of Turkey I downloaded

Data processing

Analyze the data

open qgis, Load data , In the Middle East: geo4-2l It is a generalized geological document ,flt4_2l It means

We can see that there are many polygons on this data , If you want to know what they mean , You can use the recognition tool to check each one

But if you want to look at the overall data , This may not work well , You can try right clicking on the layer in the content pane , Select property sheet to view

But I think it's hard for you to be interested in this all English attribute list , Although I can't understand , But we can try to infer

Well, I can't guess , Maybe geological type ？ No more guessing , We can find descriptions of these properties on the previous website

They are all in this brief report ,

Open these reports , You can see the professional noun corresponding to the attribute , Metamorphic rocks these , I'm sorry I gave my geology back to my teacher

Symbolization

ok , Let's go back to qgis, If you want to make this geological map according to different rock types , We need to classify and color him

Double click the symbol in front of the layer to open the properties , Select symbolization

Upload and change to classification , Select the appropriate field

The effect is as follows

Define projection

If you're careful , You should be able to find , The coordinate system of the lower right corner of the map is unknown , This means that dynamic projection really chooses , So we need to define a projection for him （ Otherwise it would be interesting to add a scale bar ）

Click unknown in the lower right corner to enter the definition projection interface

Select region

We don't really need such a large area in the mapping process , Only one country or province is needed , Next, if you have the data of the corresponding region, you can cut it directly , To extract a part of the geological map

Here comes the question , I don't have , So I just found a piece of land to show you

This should be an island , Just use it

Freehand selection

The selection results are as follows

Never mind , Export data first

The area outside the island is a whole , We can easily choose him , Then delete

Open the toggle edit mode of the digitized toolbar , Be similar to arcgis Editor for , then delete, You can delete the selected element

He's so ugly , Follow the previous method to glg Field for classification and coloring

Map layout

Establish layout

Next, let's go to layout drawing , engineering —— New print layout

direct ok Well

After entering, you can right-click on the map drawing board , To change page properties , Such as paper size

Because the island is vertical , So I changed the paper direction to vertical

Select the add map button to add a map

Draw a rectangle on the map board , If you can't master it well at the first time, you can also modify the rectangle range through the boundary line next to it later

If you move now , You will find that you are moving the rectangular layout , Not the map inside , Click the move item content button on the left toolbar to move the map

Try resizing , Make him look more balanced

Sometimes the wheel adjustment is either too large or too small , So I suggest that you can make minor adjustments by changing the scale of the toolbar on the right