19 replies to this topic

[YZT_CNG]

Hi, friends,

This topographic map is produced in Erdas. To reduce the file size (74 X 52 cm), I just upload the background image and neglect text and other imformation. Welcome your comments, Thank you!

Yu

Attached Files

•  Erdas_North_Tibet4_0.jpg   488.21K   209 downloads

[Hans van der Maarel]

Yu,

Very impressive, thanks for sharing. What did you use as source data?

Would it be possible to see a small section of this map at full scale, with the texts etc included? Since you scaled it down, it seems there's too much detail in the terrain, but on the real scale it probabely looks fine.

[frax]

nice, and very beautiful! I like the whole color scheme. I wouldn't mind seeing the map with the information on, can't you resample the output to a decent sized jpeg?

Some questions:
- where are the colors from, are they natural? I would have expected it to be quite dry and barren there.
- There is something with the relief that makes it look a bit weird to me. I feels like you maybe only are using major landforms or something?
- I would suggest experimenting with a lighter color for the lakes, and maybe some kind of effect there - inset shadow, glow or gradients (at least on the bigger ones)

[Martin Gamache]

Frax,

it appears the ligth source is from the north so the shadows are different than we are use to whihc makes it look weird to me as well. i'd like to see a sample at full resolution too.

[frax]

martin, that too (I actually tried and looked at the map upside down too) - but there is something else... maybe the vertical exagerattion is too high or something?

[Martin Gamache]

Especially in the southeast corner, where you get what I call the "melting wax mountain" look.

It looks like a MODIS image draped over GTOPO 30. I think there are parts of the year when the Tibetan plateau greens up...

[BEAVER]

Few things I see that need some changing IMHO. The blue lakes do not cover the satelite image lakes in many spots. The red border line looks like it was done with paint brush in photoshop or something like that. It looks blurry and it's too wide for my taste. The rivers blend in with the green terrain in may places making them hard to see.

[DaveB]

- I would suggest experimenting with a lighter color for the lakes, and maybe some kind of effect there - inset shadow, glow or gradients (at least on the bigger ones)

<{POST_SNAPBACK}>

Maybe sun glints like Tom Patterson shows in cartographic realism (see figure 7 in this article).

By the way, this article was published in Cartographic Perspectives (No. 43) Fall 2002.

[YZT_CNG]

Hans van der Maarel, frax, Alpine Mapping Guild, BEAVER, DaveB,

Many thanks for your comments and encouragement. I want to upload a clear image, but failed, due to the 500k limit of uploaded file. I have to process the files and reduce them as little as i can. Wish you can see the detailed part then.

the terrain file is 100m res. of grid (arcinfo version) resulting from 1:250,000 contour file. But it's too detailed for such a large area, which is equal to 6 california or so. In erdas, I have to set down the show detail, samiliarly decreaseing the resolution of the dem.

The satellite is ETM of 30m res. The original ETM is merged from band 7, 4, and 2, so it's false color. After convert it into Tif version, I modify it near to natural color, according as the physiognomy zone. For example, the Caidamu Basic is a very dry basin, with some fan-like oasises in the end of river. I made the color of this area like dry. In addition, the northeast of the map is the verge of west Loess Plateau. Originally, the ETM image shows green. But to approach to the landscape we are familiar with, I modify it near to yellow. Then I attached projection to the tif file, overlayed on it other vertor file, like river, city, province line, in arcmap. Output them respectly, overlay them in photoshop and modify them further. In the end, drape it on the terrain file in erdas. Set light, angle, show detail, and so on. In the end, output it and adjust it further in ps. I add city and river name in illustrator and large area of texts in pagermaker, because illustrator cannot deal with interpunction of Chinese characters correctly.

Because the area is too large, I make the angle near to flat. If incline a big angle, some mountain area would show broken-up. To project the mountain effect, I have to exagerat the vertical direction greatly. It looks really weird, as Alpine said.


some problems:

1. the ETM (band742) is false color. I don't know how to adjust it to real natural color. I know terracolor can do it. see

http://www.terracolor.net/

But terracolor's images are so valuabe that I cannot afford them. Do you know how to adjust to terracolor-like effect?

2. Compared with some 3d software, Erdas doesn't have advantages in rendering and lighting effect. You can see the mountain shadow is very dark. Modifying it later is rather a great job. But in my view, erdas has two merits: having very fast speed in processing very large raster data; adjusting the show resolution detail expediently.

Bryce is great in processing rendering and lighting effect. But it's slow and adjust the dem detail. As usual, I bump it in ps and test the effect in bryce. A good news comes that Bryce can load large area of dem, just dividing dem into several square tiles and overlaying corresponding images. I'm trying it. I wish erdas can combine the merits of bryce, or just the reverse.

[YZT_CNG]

sorry, I have forgotten the whole image of Qinghai province. Next week I'll upload it. Now I'll upload some part of it and other images processed by Bryce.

Caidamu Basic:
 Caidamu_Basin.jpg   490.04K   154 downloads

Qinghai Lake and Loess Plateau
 Qinghai_Lake_and_Loess_Plateau.jpg   473.28K   152 downloads

[YZT_CNG]

The speed of uploading is rather slow. Anyway, who can tell me a website where I can upload large image files?

Other part of Qinghai Province:

 qh_04.jpg   422.03K   127 downloads

the next image have most equal area of the origin of Yangtze River:

 qh_11.jpg   473.52K   138 downloads

[Martin Gamache]

Yu,

It is possible to modify the colors of the Geocover dataset in Photoshop.

Due to the size and scale of your map (what is the scale?) I would recommend you look at the MODIS 500m reflectance datasets. It may be that you can get very good natural color (using bands 1,4,3) and cloud free coverage.


The GLCF has such data and you can use the free MODIS tools to reproject and clip out areas of interest for import into ERDAS.

[YZT_CNG]

The following image is the origin area of Yangtze River, Processed by Bryce:

the whole image with text:
 texts.jpg   473.84K   179 downloads

some parts of the image without text:
 origin7_1_02.jpg   256.9K   119 downloads

[YZT_CNG]

other parts:

 origin7_1_03.jpg   248.56K   127 downloads


 origin7_1_05.jpg   319.9K   116 downloads

 origin7_1_06.jpg   290.57K   119 downloads

[YZT_CNG]

Thank you, Alpine,

I'll use modis (143) to take a try later. I seem to remember some disadvantages of band 143 from terracolor's white paper. I'm not sure now, but i'll try it.

I don't know the scale because i'm in home now. I'll post it next week.

Yu